DEVELOPMENT OF SAGO STARCH PROCESSING EQUIPMENT ( サゴヤシデンプン抽出装置の開発研究 )

Transcription

1 Ph.D. Thesis DEVELOPMENT OF SAGO STARCH PROCESSING EQUIPMENT ( サゴヤシデンプン抽出装置の開発研究 ) Graduate School of Bioresources Mie University, Japan DARMA March, 2015

2 Ph.D. Thesis Development of Sago Starch Processing Equipment ( サゴヤシデンプン抽出装置の開発研究 ) Darma 512D205 Laboratory of Energy Utilization Engineering Graduate School of Bioresources Mie University 2015

3 i PREFACE In the name of Allah the compassionate the merciful. Sago starch processing is purposed to extract the starch from sago trunk. It can be classified into three categories namely traditional processing, mechanical processing and combination of the two. Traditional method of sago starch processing was a time and labor intensive process. In addition, the starch has been produced was low quality grade. In contrast, mechanical processing has relatively shorter processing time and more hygienic process and producing high quality starch. However, the principles and methods of sago starch processing are similar for both traditional and mechanical one, differing only in the scale of operation and the equipments have been used. Up to the present time, in most part of the main producer area of sago such as Indonesia and Papua New Guinea, starch was extracted using traditional method. This method was ineffective and inefficient, consequently, the starch production was very low both in term of quantity and quality. Millions of tons of the starch was not harvested and lost every year. In order to increase sago starch production in those areas, farmers should apply mechanical method of starch processing. Applications of mechanical equipment in the form of appropriate technology are suitable for most developing countries. Imported high-technology mechanical equipment not only has a high price but also need a high skill to operate them. In doing so, it is necessary to provide mechanical equipment which is suitable and easy to use by ordinary farmers. Mechanical sago starch equipments that were developed in this research were encouraged by the problems faced by sago farmers. They were intended for small scale processing of sago starch because it was considered suitable to be applied in most sago

4 ii producing area such as in Papua and Papua New Guinea. It consists of two separately operation unit namely cylinder type sago rasper and stirrer blade type sago starch extractor. This dissertation entitled DEVELOPMENT OF SAGO STARCH PROCESSING EQUIPMENT describes the result of the five consecutive experiments which were conducted with respect to the topic. It commence with introduction chapter contains an overview of knowledge with regard to the sago starch processing and the related aspects, followed by research chapters pertaining to the development of cylinder type sago rasper and development of stirrer rotary blade sago starch extractor. It is expected that the application of the mechanical sago starch processing equipment that was resulted in this study will help the sago farmer to increase the production of sago starch.

5 iii ACKNOWLEDGEMENT All praise be to God, Allah the most Gracious most Merciful without Whose Will, this dissertation would not be completion on time. I am indebted to many peoples who gave valuable contributions up to the completion of this dissertation. First of all, I would like to express my special appreciation and thanks to my principle supervisor Prof. Xiu Lun Wang, Ph.D for his dedicated guidance and supervision throughout this study. Since well before I started Ph.D program, he has dedicated considerable time to facilitate me to enter to Mie University, Japan. Without his acceptance in Energy Utilization Engineering Laboratory, I would never have the opportunity to pursue Doctoral Program at Mie University. His advice on both research as well as on my whole study have been priceless. I also would like to thank to him for providing research facilities and instruments without which the current research would not have been possible. I am forever indebted to him for his assistance, motivation and support during my study and helped make this dissertation accomplished. Sincerest thanks also extended to my second supervisor Assoc. Prof. Dr. Koji Kito who gave useful suggestion and comments in the routine seminar. I would also like to thank my committee members, Prof. Kunio Sato, Ph.D and Prof. Ho Jinyama, Ph.D for their helpful advices and constructive criticisms as well as for serving as my committee members. My gratitude and appreciations are extended to Prof. Dr. Hiroshi Ehara for his introduced me to Prof. Xiu Lun Wang, Ph.D. He gave the opportunity to continue my study at Mie University and also gave useful information and guidance to enter to Mie University. I would also like to express my deep appreciation to Mr. Floyd McDaniel for manuscript checking and correcting the English spelling and grammar. He also gave many useful comments and suggestions for improving the quality of both paper for journal publication and this dissertation. Many thanks are also expressed to Ms. Tingting Wu, my senior fellow, for her useful assistance in many case particularly Japanese s culture and language throughout my study. I am very appreciative of the financial support I received in the form of Directorate General of Higher Education (DGHE) scholarship for three years period. This scholarship was provided by Directorate general of Higher Education (DGHE) Ministry of Education and Culture of Republic of Indonesia. Without that support, completion of my

6 iv doctoral program would have been considerably difficult. Sincerest appreciation also extended to Dr. Ir. Merlyn Lekoto, MS (previous rector of State University of Papua) and Dr. Suriel S. Mofu, S.Pd. M.Ed. M.Phil. (rector of State University of Papua) for their permission to me to continue study abroad. I am also very appreciative of the hospitality and kindness of all academic staffs within the Faculty of Bioresources, Department of Environmental Science and Technology and Centre for International Education and Research (CIER), Mie University. They have been full of dedicated and wonderfully helpful, patient, and understanding of my difficulty in Japanese speaking. Sincerest thanks also extended to all fellow students in the Energy Utilization Engineering Laboratory, Department of Environmental Science and Technology, Faculty of Bioresources, Mie University who always helped me in many cases and occasions. Special thanks are also extended to Mr. La Tandri, Mr. Sirajuddin, Mr. Mansur, Mr. Paul Giban, Mr. Basrum, and Mr. Jalaluddin who helped me conducting experiment. They have been very helpful since preparing materials for construction up to performance testing of the equipment. I am likewise grateful to my parents who always pray for my success. I believe their prayer made me keep doing the right thing and made every effort became easier. I am greatly indebted to my beloved wife, Nurmiati, my lovely daughter Nur Annisa, Chusnul Azisah, Nurul Ihza, and my dearest son Fahmi Ilman who supports me with her endurance, encouragement, great patience and understanding throughout my study abroad. Finally, I thank to everyone might have not mentioned in this acknowledgements who helped me during my study. May God, Allah Almighty bless them with the best of rewards. Tsu, Maret 2015 D A R M A

7 v SUMMARY Sago starch, produced from sago palm (Metroxylon spp.) has long been an important source of nutrition throughout the South East Asian archipelago and in some parts of Melanesia, certain islands of Micronesia, and various areas of tropical South America. The starch has a multitude of uses. It has wide utilization in numerous industries both for food industries and non-food industries. Among those sago producer countries, Indonesia has the largest sago potential with the total area of sago palm stands about 1,398,000 ha. However, unfortunately, the sago starch production and utilization is very small comparing with its potential. Millions of tons of the starch is not harvested and disappear every year. This is because of farmers in this area still use traditional method to process sago starch which are inefficient and ineffective. Up to the present time, there has been no significant increase in sago starch production in Indonesia especially in West Papua where about 95% of the Indonesia s sago potential existed. In contrary, in Serawak, Malaysia, even though the sago potential was small, it was the world biggest exporter of sago starch. The sago starch industry in Malaysia is well established and has become one of the important industries contributing to export revenue. In order to increase sago starch production, farmers should change the traditional method with mechanical one. With regard to the mechanical processing, it is necessary to provide mechanical equipment which is suitable and easy to use by common farmers. The objective of this study was to develop sago starch processing equipments in order to improve their performance. The equipments to be developed were intended for small scale (household) processing of sago starch because it was considered suitable to be applied in most sago producing area such as in Papua and Papua New Guinea. It consists of two separately operation unit namely cylinder type sago rasper and stirrer blade type sago starch extractor. Overall, this study consists of five consecutive experiments; each was discussed in different chapter. In addition, there was another chapter, introduction (chapter 1) which contains an overview of knowledge with respect to the background and significance of this study, importance and distribution areas of sago palm in the world, main production areas of sago starch, utilization of sago starch, processing of sago starch, the objective and the scope of this study. Development of cylinder type sago rasper for improving rasping performance (chapter 2). The objective of this experiment was to develop cylinder type sago rasper in

8 vi order to improve its rasping performance. In this experiment, three densities of teeth distribution on the cylinder surface (2.2 cm 4 cm distant, 2.2 cm 3 cm distant and 2.2 cm 2 cm distant) and five level of cylinder rotation speed (745 rpm, 1490 rpm, 2235 rpm, 2980 rpm, and 3725 rpm) were examined. Rasper s performance test was carried out by measuring the parameter of rasping torque requirement, rasping efficiency, starch percentage, starch yield, power requirement and starch yield efficiency. The experimental results showed that the higher the cylinder rotation speed, the lower the rasping torque requirement, while the higher the density of cylinder s teeth, the larger the rasping torque requirement. The highest rasping efficiency ( kg/hour) was resulted under experimental condition of teeth density 2.2 cm 4 cm distant at cylinder rotation speed of 2235 rpm; The highest starch percentage (26.44%) was obtained at experimental condition at teeth density 2.2 cm 4 cm distant with cylinder rotation speed of 1490 rpm; The highest starch yield was kg/hour resulted under experimental condition at teeth density of 2.2 cm 4 cm distant with cylinder rotation speed of 2235 rpm; The highest starch yield efficiency (92 kg/kwh) was obtained at the condition of teeth density 2.2 cm 3 cm distant with cylinder rotation speed of 1490 rpm. Therefore, teeth density 2.2 cm 4 cm distant with cylinder rotation speed of 2235 rpm was the optimum condition for rasping operation in which resulted the highest performance of the rasper. Improvement of cylinder type sago rasper using pointed teeth (chapter 3). Based on previous experiment results (chapter 2) revealed that developed cylinder type sago rasper works properly and has high performance compared with existing prototype which using blunt teeth. Therefore it was able to be used as a basic form to develop further in actual size. This experiment purposes to develop further the sago rasper that has been developed in previous experiment. Principally, this experiment was similar to previous experiment, but differs only in the power source which is used and the frame was simpler because not equipped with torque meter device. Unlike with previous experiment which is driven by 2 hp electric motor, in this experiment it is driven by 6.5 HP gasoline engine. Moreover, there were only three level of cylinder rotation speed to be examined (1500 rpm, 2250 rpm and 3000 rpm), while teeth density was identical with previous experiment (chapter 2). The results revealed that the best experimental condition to produce highest rasping efficiency as well as starch yield was teeth density 2.2 cm x 4 cm distant with cylinder rotation speed of 2250 rpm. In the condition the rasping efficiency and the starch

9 vii yield were 1009 kg/hour and 476 kg/hour respectively. In conclusion the improved sago rasper resulted in this study works properly and has high performance. Variant -2 of improved cylinder type sago rasper (chapter 4). At present time, the existing sago rasper that is widely used for household operation in West Papua Province, Indonesia is cylinder type with blunt teeth. The process system of this rasper was hard wooden cylinder 15 cm in diameter and 20 cm long. The teeth were made of stainless steel rod 4 mm in diameter and 2 cm height. The rasper was driven at 3000 rpm by 5.5 hp gasoline engine. This experiment aims to investigate the rasping performance of three different teeth density as mentioned previously in chapter 2 and chapter 3 when they driven with 5.5 hp gasoline engine at 3000 rpm. In general, this experiment was similar to the previous experiment (chapter 3), except for the power source which was used. In addition, there was only one speed of cylinder rotation that was tested namely 3000 rpm. The results revealed that lower density of cylinder s teeth resulted higher rasping efficiency as well as starch yield. The highest rasping performance was resulted from teeth density of 2.2 cm x 4 cm distant. The rasper s performance at the condition were rasping efficiency 635 kg/hour, starch percentage % and starch yield 142 kg/hour. This performance was higher compared to the performance of existing sago rasper. Development of sago starch extractor with stirrer rotary blade for improving extraction performance (chapter 5). Extraction process is aimed to remove maximum amount of fibre possible from the starch and to obtain the maximum amount of starch. The efficiency of the extraction depends on how carefully the operation is managed. The principles of starch extraction are to suspend or to dissolve the starch into water and then stirred rigorously to release the starch. The suspended starch or starch slurry is then separated from the fibre using a screen/sieve. The objective of this study was to develop stirrer blade sago starch extractor in order to improve its extraction performance with the focus on the effect of rotating speed of stirrer rotary blades and number of stationary blades. In the experiment, three levels of rotating speed of stirrer blades (100 rpm, 150 rpm and 200 rpm) and four levels of stationary blade numbers (no blade, 4 blades, 8 blades, and 12 blades) were examined. The extractor s performance test was carried out by measuring extraction efficiency, starch percentage, starch yield, and starch left in sago pith waste (hampas). Results showed that the higher the rotating speed, the higher the extraction efficiency, starch percentage, and starch yield. Meanwhile, the higher the rotating speed the lower the starch left in hampas. Likewise, the greater the number of

10 viii stationary blade the higher the extraction efficiency, starch percentage, and starch yield while the starch left in hampas was lower. The highest extraction efficiency of 491 kg/hour, starch percentage of %, and starch yield of 101 kg/hour and not at all starch left in hampas was resulted at the experimental condition of 12 stationary blades and rotating speed of 200 rpm. Therefore, the optimum condition to achieve highest extraction performance was 12 stationary blades with rotating speed of 200 rpm. Variant -2 of improved stirrer blade type sago starch extractor (chapter 6). Previous research (chapter 5) has shown that extraction performance was influenced by both stirrer blades rotating speed and the number of stationary blades. However, it is necessary to be investigated further the effect of stirrer rotating speed as well as number of stationary blades on extraction performance when using screener with smaller holes. It may be expected that smaller holes of screener will give higher performance. In general, this experiment was similar to previous experiment (chapter 5), except for the screener have been used. Furthermore, the diameter of extraction cylinder was larger but shorter in height. This was aimed to increase the cylinder capacity as well as to make it easier to feed the repos into the extraction cylinder. The dimension of second stage screen was made larger so that it will not full in one process of extraction. By doing so, it was easier to handle the fine hampas, thus less time was needed to discard them. Experimental conditions as well as parameters to be measured were same as previous one (chapter 5). Results revealed that the higher the rotating speed of stirrer blade, the higher the extraction efficiency, starch percentage, and starch yield. Meanwhile, the higher the rotating speed the lower the starch left in hampas. Similarly, the greater the number of stationary blade the higher the extraction efficiency, starch percentage, and starch yield while the starch left in hampas was lower. Based on the results of this study suggests that the optimum condition of extracting sago starch was 12 blades of stationary blades with rotation speed of stirrer blade 200 rpm. This condition resulted highest extraction efficiency, starch percentage, starch yield, and resulted the lowest starch left in hampas. Compared to the previous results (chapter 5), this result was doubled higher. In conclusion, the extraction performance of Variant -2 was higher than previously.

11 ix TABLE OF CONTENTS Content Page PREFACE... ACKNOWLEDGEMENT... SUMMARY... TABLE OF CONTENTS... LIST OF FIGURES... LIST OF TABLES... CHAPTER 1. INTRODUCTION BACKGROUND AND SIGNIFICANCE OF THIS STUDY IMPORTANCE AND DISTRIBUTION AREAS OF SAGO PALM IN THE WORLD MAIN PRODUCTION AREAS OF SAGO STARCH UTILIZATION OF SAGO STARCH PROCESSING OF SAGO STARCH THE OBJECTIVES OF THIS STUDY THE SCOPE OF THIS STUDY CHAPTER 2. DEVELOPMENT OF CYLINDER TYPE SAGO RASPER FOR IMPROVING RASPING PERFORMANCE EXPERIMENTAL MATERIALS AND METHODS RESULTS AND DISCUSSIONS CONCLUSIONS CHAPTER 3. IMPROVEMENT OF CYLINDER TYPE SAGO RASPER USING SHARP POINTED TEETH EXPERIMENTAL MATERIALS AND METHODS RESULTS AND DISCUSSIONS CONCLUSIONS CHAPTER 4. VARIANT-2 OF IMPROVED CYLINDER TYPE SAGO RASPER EXPERIMENTAL MATERIALS AND METHODS RESULTS AND DISCUSSIONS CONCLUSIONS i iii v ix xi xvi

12 x CHAPTER 5. DEVELOPMENT OF SAGO STARCH EXTRACTOR WITH STIRRER ROTARY BLADE FOR IMPROVING EXTRACTION PERFORMANCE EXPERIMENTAL MATERIALS AND METHODS RESULTS AND DISCUSSIONS CONCLUSIONS CHAPTER 6. VARIANT-2 OF IMPROVED STIRRER ROTARY BLADE TYPE SAGO STARCH EXTRACTOR EXPERIMENTAL MATERIALS AND METHODS RESULTS AND DISCUSSIONS CONCLUSIONS REFERENCES SAGO STARCH PROCESSING TERMINOLOGIES APPENDIX

13 xi LIST OF FIGURES No. Titles Page Figure 1.1 Figure 1.2 Figure 1.3 Distribution Area of Sago in Indonesia...5 Aerial photo of mixture of sago and other species (a) and nearly pure sago forest (b)...5 Natural sago forests with high percentage of mature palm (a) and high density of sago trunk with different stages of growth (b)...5 Figure 1.4 Distribution of sago-yielding palms in the old world...9 Figure 1.5 Figure 1.6 Figure 1.7 Distribution of sago-yielding palms in the new world...10 Distribution of sago palms in the South Pacific islands, extending Westward through Melanesia into Indonesia, Malaysia, and Thailand...10 Papeda, glue-like mass made of sago starch ready to consume...13 Figure 1.8 forna, sago lempeng mold (a) and sago lempeng (b)...13 Figure 1.9 Applications of sago palm...17 Figure 1.10 Figure 1.11 Figure 1.12 Figure 1.13 The trunk is cutting down (a), after being felled, it is then split into two sections (b) or stripped back the bark to exposes the pith of the trunk (c)...19 Pounder made of hard wood with metal ferrule at the blade end, handle and blade fastened with rattan...20 Disintegration of sago pith using traditional pounder...20 Traditional extraction of sago starch...21 Figure 1.14 Wet sago starch collected in basket made of sago leaves...21 Figure 1.15 Figure 1.16 Figure 1.17 Figure 1.18 Flow diagram of modern sago starch processing...23 The sago trunk (a), after being felled, it is then cut into several sections, 1 to 1.2 m long (b)...24 The sago logs are tied into rafts and transported to the plan via rivers...24 Sago logs are debarked using either an auto debarking machine or manually with a machete...25

14 xii Figure 1.19 Rasping of debarked sago log sections to release starch granules from disintegrated fibres...26 Figure 1.20 Bagged sago starch ready for export...25 Figure 2.1 Figure 2.2 Figure 2.3 Figure 2.4 Figure 2.5 Scanning Electron Micrograph of freed sago starch granules...33 Cylindrical rasping surface in good condition (a) and the nails have already worn down (b)...35 Cylinder type sago rasper that is used widely in small scale operation of sago starch processing in Papua Province, Indonesia...36 The rasping cylinder before their surface were embedded with the teeth...37 Rasping cylinder: density 1 (a), density 2 (b) and density 3 (c)...38 Figure 2.6 Construction of sago rasper for experiment...38 Figure 2.7 Figure 2.8a Figure 2.8b Figure 2.8c Figure 2.9 Front view (a) and side view (b) of experimental sago rasper developed in this study...39 The arrangement pattern of the teeth density-1 (D1) on cylinder s circumference surface...40 The arrangement pattern of the teeth density-1 (D1) on cylinder s circumference surface...41 The arrangement pattern of the teeth density-3 (D3) on cylinder s circumference surface...41 Feature of rasping cylinder...42 Figure 2.9 Feature of cylinder s teeth...42 Figure 2.10 Experimental setting and instruments for torque measurement...43 Figure 2.11 Splitting and debarking sago logs (a) and sago rasping process (b)...44 Figure 2.12 Rasped pith ready to be processed further to extract the starch...45 Figure 2.13 Figure 2.14 Figure 2.15 Relationship between rasping torque requirement and cylinder rotation speed...46 Relationship between rasping efficiency and cylinder rotation speed...47 Relationship between starch percentage and cylinder rotation speed...49

15 xiii Figure 2.16 Figure 3.1 Figure 3.2 Relationship between Starch yield and cylinder rotation speed and corresponding rasping power requirement...51 Construction of cylinder type sago rasper powered by 6.5 hp gasoline Engine...56 The Rasping cylinder of D1, D2, and D Figure 3.3 Cutting the sago trunk into logs (a) and the logs ready to transport (b)...58 Figure 3.4 Figure 3.5 Figure 3.6 Debarking and splitting the logs before rasping (a) and sago rasping process (b)...58 Starch extraction using stirrer rotary blade sago starch extraction (a) and wet sago starch ready to weighed (b)...60 Relationship between rasping efficiency and cylinder rotation speed...60 Figure 3.7 Relationship between starch percentage and cylinder rotation speed Figure 3.8 Relationship between starch yield and cylinder rotation speed...63 Figure 4.1 Figure 4.2 Figure 4.3 Figure 4.4 Figure 4.5 Existing sago rasper that is recently used in West Papua, Indonesia...66 Construction of cylinder type sago rasper powered by 5.5 hp gasoline Engine...66 The Rasping cylinder of D1, D2, and D Rasping efficiency at teeth density D1, D3, D3 and ER...68 Starch percentage at teeth density D1, D3, D3 and ER...69 Figure 4.6 starch yield at teeth density D1, D3, D3 and ER...70 Figure 5.1 Screen material made of fine cloth...74 Figure 5.2 Screen material made of fibrous leaf sheath of coconut...74 Figure 5.3 A rotating sago starch screen...76 Figure 5.4 Integrated Sago Processing Machine...76 Figure 5.5 Stirrer rotary blade sago starch extractor...77 Figure 5.6 Stirrer rotary blade sago starch extractor...78 Figure 5.7 Overall structure of stirrer rotary blades sago starch extractor...80

16 xiv Figure 5.8 Screener was ready to be assembled (a) and it already to be mounted in the extraction cylinder (b)...81 Figure 5.9 Functional components of the extractor...81 Figure 5.10 Overall process flow chart of sago starch processing...82 Figure 5.11 Figure 5.12 Figure 5.13 Figure 5.14 Figure 5.15 Figure 5.16 Figure 5.17 Figure 5.18 Rasped pith ready to be processed (a) and input the rasped pith int the extractor (b)...83 Sago pith waste (hampas) was discarded out manually from extractor...84 Supernatant water was drained out (a) and fresh starch was taken out and thenweighed (b)...84 Starch suspensions in sedimentation tank (a), after 2 hours starch was Settled at the bottom of the tank (b), then supernatant water was drained out and fresh starch ready to be taken out(c)...85 Manually sago starch extraction to re-extract the starch left in hampas...86 Relationship between stirrer blades rotating speed and extraction Efficiency...87 the flowing pattern of repos slurry in the cylinder extractor: (a) turbulent flowing of water (b) high intensity of turbulent flowing of repos slurry...89 Empty space in the centre of cylinder (a) and steady state flowing of repos slurry (b)...89 Figure 5.19 Relationship between stirrer blades rotating speed and starch percentage..92 Figure 5.20 Relationship between stirrer blades rotating speed and starch yield...92 Figure 5.21 Relationship between stirrer blades rotating speed and starch loss in hampas...94 Figure 5.22 Sago pith waste called hampas...96 Figure 6.1 Figure 6.2 Second stage of screener was made fine cloth with wooden frame...98 Overall structure of Variant-2 stirrer rotary blades sago starch extractor..101 Figure 6.3 Screener was ready to be assembled (a) and second stage screener (b) Figure 6.4 Screener with stationary blades in which extractor ready to be operated (a) and extraction process is occurring (b)...102

17 xv Figure 6.5 Figure 5.6 Figure 5.7 Relationship between stirrer blades rotating speed and extraction efficiency The flowing pattern of repos slurry in the cylinder extractor Turbulent flowing of repos slurry in the extraction cylinder Figure 5.8 Relationship between stirrer blades rotating speed and starch percentage 106 Figure 5.9 Relationship between stirrer blades rotating speed and starch yield Figure 5.10 Relationship between stirrer blades rotating speed and starch loss in hampas

18 xvi LIST OF TABLES No. Titles Page Table 1.1 Palm genera exploited for stem starch...8 Table 1.2 Rough estimate of area (ha) covered with good quality sago palm stands..11 Table 1.3 Table 1.4 Utilization of sago starch in food industries...15 Utilization of sago starch in food industries...16

19 1 CHAPTER 1. INTRODUCTION 1.1. Background and Significance of this Study The sago palm (Metroxylon sagu Rottboel) has long been an important source of nutrition throughout the South East Asian archipelago (Cecil at al., 1992; Flach, 1997) and in some parts of Melanesia, certain islands of Micronesia, and various areas of tropical South America (Ruddle, 1978). Starch from the stem of palms is an important product in those regions. At present time, this starch is an important food source among some native peoples in several parts of Indonesia, Papua New Guinea, Malaysia, and Philippines. Besides is used as staple food, complementary food, and animal feed, it is also used as raw material for agroindustry, bio-pesticide, bio-ethanol, bio-degradable plastic, cosmetic, and pharmaceutical industry (Haryanto and Pangloly, 1992; Bintoro, 2011; Ishizaki, 2009), as well as raw material for sugars production (Bujang, 2011). The palm is able to thrive in swampy areas or peat soils and grows naturally without the need for pesticide and herbicide, and it is the highest starch producer compared with other starch producer crops (Djofrie, 2004; Bintoro, 2011). It will be recognized as an important crop for starch-based industries in the 21 st century (Jong, 1995). In Indonesia, sago palm can be found scattered in almost all part of the country except DKI Jakarta, Yogyakarta, West Nusa Tenggara and East Nusa Tenggara Province. (Figure 1.1). In recent time, in some parts of Indonesia, the cultivation of rice, maize and cassava has gradually replaced sago. However, sago remains important as subsistence foodstuff in many parts of the country such as the Mentawai Islands, Bangka and Billiton Islands, Riau, Eastern Sumatra, Bali, Lombok, Kalimantan, Sulawesi, Molucca and West Papua. Within Indonesia, Molucca and West Papua is the area most strongly associated

20 2 with dependence on sago for staple food for indigenous people (Manan and Supangkat, 1984; Haryanto and Pangloly, 1992; Matanubun et al., 2006; Wardis, 2014). Indonesia has the largest sago potential with the total area of sago palm stands about 1,398,000 ha (Flach, 1997). Manan and Supangkat (1984) estimated an even greater total sago area in Indonesia is around 4,000,000 ha. More than 50 % of the total world sago palm stands were grown in Indonesia and 95 % of it was located in West Papua Province. Flach (1997) estimated a total of 1,200,000 ha wild stands (natural sago forest) and 14,000 ha stands of semi cultivated sago palm was located in West Papua. Meanwhile, Matanubun and Maturbong (2006) stated that sago palm stand in West Papua is approximately 1,471,232 ha, which mostly natural sago forest (Figure 1.2). By using the area of 1,471,232 ha, Matanubun and Maturbong (2006) predict the sago starch production potential in West Papua is about 12,035,555 tons/year. According to Bintoro (2011), the potential yield of natural sago forest is around tons starch/ha/year. It means that the total potential yield of sago in this region is around 29,424,640-58,849,280 tons/year. The most recently research conducted by Jong and Ho (2011) concluded that in the natural sago forest in South Sorong, West Papua, dry starch yield potential was between tons/ha/year. Therefore, the total dry starch yield potential was between 14,712,320-22,068,480 tons/year. Although Indonesia has the largest potential of sago in the world, unfortunately, the sago starch production and utilization is very small comparing with its potential. Millions of tons of the starch is not harvested and disappear every year. According to Samad (2002), the utilization of sago palm resources in Indonesia is only about 0.1 % of its total potential. Matanubun and Maturbong (2006) stated that utilization of sago resources in West Papua, which has over 95 % of Indonesia s sago palm, is less than 5 % of its existing potential. Up to the present time, farmers in this region cut sago trees and process mainly for

21 3 subsistence use and sell locally but they exploit only a very small amount compared with its potential. Consequently, a large number of mature sago palm are not harvested and lost every year. Meanwhile the current demand for sago starch, both for local and global markets, increases continuously. There has been no significant increase in sago starch production in West Papua. Unlike in Serawak, Malaysia, even though the sago potential was small, it was the world biggest exporter of sago starch with total export of 44,700 tons in 2007 (Bujang, 2011; Singhal et al., 2008; Karim et al., 2008). The sago industry in Malaysia (in the State of Serawak) is well established and has become one of the important industries contributing to export revenue (Karim et al., 2008). A traditional method of sago starch extraction is now being used in most parts of West Papua and is mainly for subsistence. It is well known that traditional method of sago starch processing was a time and labor intensive process. Consequently, sago starch production is very low, both in quantity and quality. Farmers in this area continue to use traditional systems to process sago starch because the lack of mechanical equipment. The industrial technology of processing starch and its derivatives from potato, cassava, maize, rice and wheat has developed very well. However, this is not the case with sago starch technology. There are only a few simple technologies besides traditional method. The principles and methods of sago starch processing or sago starch extraction is almost the same for both traditional and mechanical production, but differs only in the equipment which is used and the scale of operation (Kamal et al., 2007; Rajyalakshmi, 2004, Karim et al., 2008). The purpose of the extraction is to separate starch from the cellulosic cell walls of the trunk. This procedure is: (1) Palms are selected and felled, (2) Clearing, debarking and splitting the logs, (3) Disintegration or breaking down the pith of log, (4) Starch extraction/separation of starch, (5) Starch sedimentation and dewatering, (6) Starch drying and packaging. The traditional method of sago starch extraction not only

22 4 ineffective and inefficient but also the starch quality produced is low. In contrast, mechanical processing of sago palm, beside much more effective and efficient, the starch produced has higher quality and is more hygienic (Karim et al., 2008; Singhal et al., 2008). Therefore, farmers in this area should change the traditional method with mechanical one in order to increase sago starch production. With regard to the mechanical processing, it is necessary to provide mechanical equipment that are suitable and easy to use by common farmers. Mechanical processing of sago will transform the traditional agricultural system into a developed and commercial agriculture and as a result is increase of farmers income. Agricultural mechanization plays an important role because of its contribution in improving efficiency and productivity of agricultural resources. The application of mechanical technology in the form of appropriate machinery and equipment (appropriate technology) to the farmers in developing countries such as Indonesia is suitable to be applied. The characteristics of the technology are simple, low cost, small scale and labor intensive. In addition, a region should have to develop its mechanical equipment suitable for local conditions thus its application does not meet any constraints. Application of mechanical equipment in some areas should pay attention to the various aspects of sociocultural of local community otherwise applications will be unsuccessful. For instance, Sembiring et al., (1998) stated that the failure of agricultural mechanization in Sri Lanka due to the application of imported agricultural machinery directly, unlike the Japanese who make modifications according to local conditions, and then produce their own for use by their farmers. Further stated by Sembiring et al. (1998), the development of agricultural mechanization in Indonesia to regain, maintain and increase food production should be done with the development of locally specific of agricultural mechanization.

23 5 Figure 1.1 Distribution Area of Sago in Indonesia (Bintoro, 2011) (a) (b) Figure 1.2 Aerial photo of mixture of sago and other species (a), nearly pure sago forest (b) (Photos were adapted from Jong and Ho, 2011) (a) (b) Figure 1.3 Natural sago forests with high percentage of mature palm (a) (Photo was adapted from Jong and Ho, 2011) and high density of sago trunk with different stages of growth (b)

24 6 1.2 Importance and Distribution Areas of Sago Palm in the World Starch from the stems of palms is a product of local importance throughout the mainland and islands of Southeast Asia, in parts of Melanesia, certain islands of Micronesia, and various areas of tropical South America, where it is obtained from the stems of some, mostly native, palm species. Palms stem starch, or sago, although often of great local importance in barter and trade, is not a major item of commerce with areas outside the humid tropics. For this reason, palm sago is often overlooked outside the producing regions, although it probably represents one of the most important food products derived from palms (Ruddle, 1978). The sago palm, which is known scientifically as Metroxylon sagu Rottboell has been described as humankind s oldest foodplant and the earliest account of the plant that reached western countries dates back to the 18th century (Ave, 1977). The trunk contains starch, used by the plant as a reserve food for flowering and fruiting. This starch has long been a staple food for humans in South East Asian archipelago, and as with most other palms, nearly all the other parts of the plant are used for subsistence. It is mainly grown in areas of the developing world, and has often been viewed as a poor man s crop (Cecil et.al., 1982; Flach, 1997). Since prehistoric times, starch extracted from the stem of the sago palm, has been used in trade amongst the islands of the Sumatra-New Guinea archipelago (Cecil et. al., 1982). It is one of the few tropical crops that can tolerate wet growing conditions, including peat swamps (Jong, 1995; Djofrie, 2004; Bintoro, 2011). It is also one of the highest starch producer compared with other starch producer crops. Its productivity was calculated to be four times that of paddy rice (Bintoro, 2011). Recently, this Sago palm is a starch producer which contributes to the economics of the Asean countries, particularly so for Malaysia and Indonesia.

25 7 Palms of at least 14 species belonging to 8 genera are exploited for sago production (Table 1.1), but of these only Metroxylon and Arenga pinnata, in the Old World, and Mauritia in the New, are of major importance as palm starch sources. The distribution of the principal Old World sago-producing palm genera, Metroxylon, Arenga, Caryota, Corypha, and Eugeissona is shown in Figure 1.4. Meanwhile, the distribution in New World is shown in Figure 1.5. Although of relatively limited range, Metroxylon is by far the most important genus exploited for stem starch in either the Old or New World. Palms of Metroxylon spp. are native to the area extending from Eastern Melanesia westward into Indonesia, Malaysia and Thailand, where domesticated are indistinguishable from wild species. At present, sago derived from palms of this genus is an important food source among some native peoples in Papua New Guinea, Indonesia and Malaysia, and cultivated Metroxylon is of importance in Malaysia and Indonesia (Ruddle, 1978; Flach, 1997; Karim et al., 2008). Beside Metroxylon, the palm of Arenga pinnata is also one of the major reported sources of palm sago in Indonesia and India. It is cultivated in India and Indonesia not only as a sourcr of starch but also has economic importance as a source of sap for toddy, sugar and vinegar. The palm has a wide geographical range, which includes South and mainland Southeast Asia, from Formosa, through the Philippines, Indonesia, Papua New Guinea to India (Ruddle, 1978; Bintoro, 2011). The genus Caryota has a wide distribution quite similar to that of Arenga, except that Caryota extends as far south as northern Australia, but not as far north as Formosa. The chief sago-yielding species is Caryota urens, a large single-stemmed palm which often reaches a height of 20 m, and bears distinctive bipinnate leaves resembling fishtails, and which occurs naturally in moist tropical forests at elevations up to 1,500 m (Ruddle, 1978; Rajyalakshmi, 2004).

26 8 Palms of the genus of Corypha also have a range which closely overlaps that of Caryota. Corypha, however, extends somewhat further east of Papua New Guinea than either Caryota or Arenga. Corypha umbraculifera is the principal sago-yielding species, and is used in South and mainland Southeast Asia, the Philippines, Indonesia, Papua New Guinea and tropical Australia as a minor source of palm sago (Ruddle, 1978). The genus of Eugeissona have the most limited distribution of any of the principal genera under consideration, being found naturally only in Peninsular Malaysia and Kalimantan. Eugeissona palms, which have an exceptionally short stem and large, erect pinnate leaves, are common as understory plants in the tropical forests within its range. Apart from Eugeissona utilis, which attains a height of 8 m, limited stem development precludes the accumulation of large quantities of starch. As such, palms of this genus are regarded as only minor sources of sago. They produce a terminal inflorescence after only 5-6 years of growth and, since there is relatively limited stem development, relatively small amounts of starch are produced (Ruddle, 1978). 1. OLD WORLD Metroxylon Table 1. 1 Palm genera exploited for stem starch (Ruddle, 1977) Genus Species Distribution area Spp. Papua New Guinea Irian Jaya (west Papua) Arenga Sagu (rumphii) pinnata (saccharifera) Papua New Guinea Kalimantan India Peninsular Malaysia Papua New Guinea Irian Jaya Philippines India Peninsular Malaysia Philippines Indonesia

27 9 Caryota Corypha Eugeissona 2. NEW WORLD Arecastrum Copernici Manicaria Mauritia Roystone aequatorialis mitis rumphiana urens umbraculifer utan insignis utilis Romanzoffianum Alba Saccifera Lexuosa oleracea Malaysia Peninsular Malaysia Kalimantan India Vietnam Sri Lanka Philippines Malaysia Madura Sulawesi Sarawak Kalimantan Malaysia Paraguay Southern Brazil Northeast Brazil Orinoco Delta Amazon Basin Orinoco Delta West Indies Figure 1.4 Distribution of sago-yielding palms in the old worl (Source:Ruddle, 1978)

28 10 Figure 1.5 Distribution of sago-yielding palms in the new worl (Source: Ruddle, 1978) Figure 1.6 Distribution of sago palms in the South Pacific islands, extending westward through Melanesia into Indonesia, Malaysia, and Thailand (source: Ave, 1977).

29 MAIN PRODUCTION AREAS OF SAGO STARCH The three main leading world producers of sago starch are Malaysia, Indonesia, and Papua New Guinea, where sago is grown commercially for the production of the starch. Vast wild stands of sago palm occur on the island of New Guinea, both in Irian Jaya, the Indonesian part, and in the independent state of Papua New Guinea. On the other hand, in Malaysia, there are not wild stands but cultivated or semi-cultivated stands. Flach (1983) gave a rough estimate of the wild and cultivated area covered with good sago palm stands as presented in Table 1.2. Table 1.2 Rough estimate of area (ha) covered with good quality sago palm stands (Flach, 1983) Location Wild stands (Semi-) Cultivated stands Papua New Guinea, total Sepik province Gulf province Other provinces 1,000, , , ,000 20,000 5,000 5,000 10,000 Indonesia, total Irian Jaya, total Bintuni Lake Plain Southern Irian Other Districts Moluccas Sulawesi Kalimantan Sumatera Riau islands Mentawei islands Malaysia, total Sabah Sarawak West Malaysia Thailand Philippines Other countries Total 1,250,000 1,200, , , , ,000 50, ,250, ,000 14,000 2,000-2,000 10,000 10,000 30,000 20,000 30,000 20,000 10,000 45,000 10,000 30,000 5,000 3,000 3,000 5, ,000

30 UTILIZATION OF SAGO STARCH Sago starch has been a highly utilized source of carbohydrates for many thousands of years. It is claimed to be one of the oldest food plant (Flach, 1997; Ruddle, 1978). The starch contains 25% amylose and 75% amylopectin (Ito et al., 1979). The starch has a multitude of uses. It has wide applications in numerous industries. It is used as a stabilizer and thickener, and as a substitute for modified corn starch. Besides its use as a foodstuff, sago starch can also be utilized to produce adhesives for paper, textiles, and plywood, as a stabilizer in pharmaceuticals, or converted to other types of foods (Flach, 1997; Singhal et al., 2007; Bintoro, 2011). Sago starch is also widely employed together with other starches in the production of mono sodium glutamate and fructose syrup for non-alcoholic drinks. The starch is now used as an economically viable feedstock for conversion to industrial sugars, and the market for sago is set to expand both as a domestic food and as a trade crop (Karim et al, 2008; Singhal et al., 2007). The many uses of sago starch are presented in Figure 1.9. Most of the other starches can be put to the same use as sago palm starch Traditional uses Sago starch has been used in various traditional food products as well as in industrial applications. The most common method of preparation for consumption is to pour hot water over the slightly sour wet starch, and stir it with a stick or a spoon. The resulting glue-like mass (Figure 1. 4) is eaten with some fish and vegetable dishes. Since sago contains virtually no fat or protein, it must be supplemented with foods obtained from hunting, fishing, gathering, or small gardens. When traveling, people often bring a tumang, a basket made of sago leaflets containing wet starch. A ball of wet sago starch is taken out of the basket and rolled in hot ashes. After some time, the black layer is peeled off and the

31 13 brown layer beneath it is eaten, together with the cooked mass underneath the brown layer (Flach 1997). It is also common to bake sago starch into lempeng (Figure 1.8), in forms made of baked clay (forna). The lempeng are usually made entirely of starch, but they may occasionally contain other foods as well, such as ground peanuts or other pulses. In the several parts of West Papua, the lempeng contain sago grub which is the larva of Capricorn beetle (Rhyncophorus ferrungineus/bilineatus). They are dipped in tea, coffee, or other fluids before consumption. Figure 1.7 Papeda, glue-like mass made of sago starch ready to consume (a) (b) Figure 1.8 forna, sago lempeng mold (a) and sago lempeng (b)

32 14 In the Moluccas, during festive periods, a kind of cookie is often prepared called bagea. These contain sago starch combined with ground seeds of the kenari tree (Canarium commune). Many other preparations can be found, e.g. cooking in a piece of bamboo, or in banana leaves, mixed with fish and vegetables (sinole). In West Malaysia, sago pearls are prepared. To make these, slightly wet starch is pressed through a sieve. The small particles of wet starch are then rolled around and heated in a pan with a round bottom until the outside has been gelatinized. The pearls are subsequently dried, sorted and sold. These pearls are often used to prepare the three palm pudding : sago pearls, cooked in coconut milk, and topped off with sugar from the sugar palm (Arenga pinnata). In Sarawak, pearls are prepared from sago palm starch, mixed with rice bran (Flach, 1997; Karim et al., 2008; Lakshmi, 2004). In Asmat, West Papua, tribals eat sago mixed with fish, meat or vegetables, wrapped in palm leaves, and roasted on an open fire. Another favourite is a long sausage about 20 cm long made of sago mixed with grubs. The most common way to eat sago is to roll it into fist-sized balls, which are then roasted on an open fire. In Andhra Pradesh the tribals store sago round the year in bags or pots for use in lean season. They prepare roti (pancake) or gruel (porridge) either solely with sago starch or in combination with ragi flour. For preparation of pancake, tribals use adda leaves (Bauchinia vahli Wight & Arn.). The flattened dough is placed in between two adda leaves and cooked on both side till the leaves become brown (Rajyalakshmi, 2004). There are many others food recipe using sago starch, for example, sinoli, ongolongol, limut rampai, sago dumplings in egg gravy, sago choy suey, sago curry, sagostuffeds untong, savory sago pancakes, sago with coconut milk, sago broth, sago hot pot, sago pudding, sago cones etc.

33 Uses in food industries Sago starch has great potential for its incorporation into foodstuff such as noodle, sauces, dry mixes, flakes, snacks and baby foods to replace more expensive starches which are imported (Suwanliwong, 1998). Sago starch is used in some small-scale industries in Sarawak and Indonesia (Table 1.2). Due to its viscous property upon gelatinization, starch has the potential to be used as thickener in the production of soups and baby food, as well as an additive in various food products (Takahashi, 1986; Karim et al., 2008; Ngudi Waluyo and Desi, 1998). It is also widely used together with with rice, corn, and potatoes in the manufacture of noodle. The noodle prepared from sago starch posses predominant characteristics that have been reported to define the quality of noodles, viz. appearance and textural factors such as translucency, colour, uniformity of appearance, mechanical strength and integrity, absence of sticky surface and soft eating property (Sowbhagya and Zakiuddin Ali, 2001). Table 1.2 Utilization of sago starch in food industries (Karim et al., 2008; Rajyalakshmi, 2004) Type of industry Noodles Chili and tomato sauce Biscuits Chips Kway teoh (flat noodles) Bread Buns Remarks on the use of sago starch 25% incorporation may cause slight change in color. Less fresh looking. 20% to 30% sago starch in the sauce is acceptable but reported to be less viscous. Moisture < 5% of starch is necessary. Product is acceptable. 20% sago starch will make kway teoh harder and darker and no difference in taste is noted. 25% sago starch is incorporated and no difference in taste, texture or color is noted. 20% of sago starch is acceptable.

34 Uses in non-food industries Sago starch has been used widely in non food industries, such as in the making of biodegradable plastic (Ishizaki, 2009), as an extender in urea formaldehyde adhesives (Sumadiwangsa, 1985; Solichin1986), as a finishing agent I the industrial production of paper, and for sizing in the textile industry. It is also a component of glue for sticking the sheets together in the plywood manufacturing industry, as well as for making glue gel and liquid glue for the paper-box industry and for offices (Bujang and Ahmad 2000), and also in the manufacture of adhesives (Haryanto and Pangloly, 1992). Like other starches, sago starch is also used in the production of ethanol (Haska and Ohta 1993), production of monosodium glutamate (Zulpilip et al., 1991), production of cyclodextrin (Solichin 1995), and in the lactate industry (Ishizaki 2002). Rajyalakshmi (2004) and Karim et al. (2008) has reviewed the utilization of sago starch in non-food industries as indicated in Table 1.3. Moreover, Singhal at al. (2007) and Bujang (2010) have reviewed in more details the use of sago starch in various applications. Table 1.3 Utilization of sago starch in food industries ( Rajyalakshmi, 2004; Karim et al., 2008) Biotechnology industry High fructose syrup Glucose syrup Dextrose monohydrate Caramel Maltose Malto dextrin/sweetener Monosodium glutamate Non-food industry Biodegradable plastic Ethanol Textile Paper Adhesive Plywood Filler in pharmaceutical

35 17 Figure 1.9 Applications of sago palm (Flach, 1983; Adapted from Flach, 1997) 1.5 PROCESSING OF SAGO STARCH The main edible food product obtained from sago palm is the starch stored in large quantities in its trunk. The purpose of sago processing is to extract starch from the sago logs. It is reported to be one of the cheapest and most readily available sources of food starch with the highest productivity per land area among other starch crops (Bintoro, 2011). There are several ways to extract the starch from the sago pith, but the principles and methods are said to be similar. Conventionally, the starch extraction is performed manually by individual farmers or domestic domestic scale sago processing plant. In contrast, modern processing is fully mechanized has relatively shorter processing time and more hygienic compared to conventional processing (Karim et al., 2008; Singhal et al., 2008). Principally, manually or traditional starch extraction is similar to the modern one, differing only in the scale of operation and the equipments have been used. In general, ready harvested palms are selected and felled. Bark-like layer is stripped from the trunk

36 18 and cut into sections or floated whole to a central processing facility. There, it is reduced to battens and rasped either manually or mechanically to pulverize the pith and loosen starch particles within the fiber. The starch is removed from the fibers by kneading with hands or trampling by feet or by a spray of water. Starch-laden water or starch suspension runs into a settling container, where the starch is precipitated and the water overflows. The starch is then removed and dried Traditional method of sago starch processing In most part of the main producer area of sago throughout Southeast Asia and New Guinea, starch is extracted using traditional method. Recently, this method is still commonly used in Papua New Guinea (Greenhill, 2006), West Papua (Darma et al., 2011), Molocca islands (Rumalutur, 1992; Girsang, 2014) and Seram (Ellen, 2004). This method is very labour intensive and time consuming, usually involving the cooperation of a small group of people or family. Traditional sago starch processing involves cutting the trunk using an axe (Figure 1.10), and then the bark is either stripped back or split into two section to expose the pith of the palm (Figure 1.11). In some places, a chainsaw is now used for cutting the trunk. The pith is disintegrated or puliverized using a pounder, an adze similar tool, as illustrated in Figure 1.11 and Close human contact with pulverized/chopped pith is commond during this stage of the process. The pulverized pith is then collected and carried manually to the extraction site. Starch is extracted from the pulverized pith by pouring water over it and kneading it in a trough, made of the large sheath base of the sago leaves (Figure 1.13). The mixture of pulverized pith and water is then forced or pressed through the filter made of fine cloth. The suspended starch that passes trough the filter is collected into a larger trough, also made of sheat base of sago leaf, where the starch separates out

37 19 trough sedimentation. It is then ready for packing using a packaging made of sago leaves sheat (Figure 1.14). (a) (b) (c) Figure 1.10 The trunk is cutting down (a), after being felled, it is then split into two sections (b) or stripped back the bark to exposes the pith of the trunk (c). The traditional method of extraction of sago starch can be classified into 2 levels, namely, the domestic level and the small-scale processing plant level (Karim et al., 2008). The domestic level is practiced by the individual farmers, where sago palms are felled and processed in the garden, thus without the need to transport the heavy trunk. After felling the trunk with an axe, it is split lengthwise. The pith is pulverized by means of a chopper or pounder (Figure 1.7). The pulverized mixture of fiber and pith is put on the wide end of a leaf sheath of the sago palm, where a sieve is placed at its lowest end. Water is added to the mixture and then the mixture is kneaded by hand (Figure 1.9). The fibers remain on the top of the sieve while the water carrying the starch granules in suspension passes through the sieve and is caught in an old dugout canoe or any suitable container. The starch settles on the bottom and the excess water flows over the sides. After kneading, the fibrous remnants are discarded and the wet starch is taken out of the canoe/container (Ruddle, 1978; Flach 1983). In the small-scale processing plant, sago trunks are cut into shorter lengths of 1 to 1.2 m and tied into rafts and transported to the plant via rivers or man-made water systems. Rasping is done using a board with nails in it. Some processors use engine-powered rasps

38 20 with which the pith is dug out of the split trunk and then rasped. The rasped pith is trampled by foot on a platform. In some operations, a rotating mesh washer made of metal or wood or screen washers are used to separate the starch and coarse fiber. The starch slurry is channeled to a small settling pond made of boards. Finally, drying of wet starch is done mostly in the sun (Ruddle 1978; Cecil et al., 1982; Karim et al., 2008). Some small cottage mills produce only lamentak (wet processed sago starch) or 2nd-grade-quality flour, which is sun-dried and unsieved wet sago starch. (a) (b) Figure 1.11 Pounder made of hard wood with metal ferrule at the blade end, handle and blade fastened with rattan. Photo was taken in Wasior, West Papua 2010 (a) and in Serui, West Papua 2010 (b) (a) (b) Figure 1.12 Disintegration of sago pith using traditional pounder. Photo was taken in Biak, West Papua 2010 (a) and in Serui, West Papua 2010 (b)

39 21 (a) (b) Figure 1.13 Traditional extraction of sago starch. Both photo was taken in Wasior, West Papua, Indonesia Figure 1.14 Wet sago starch collected in basket made of sago leaves, called tumang Mechanical method of sago starch processing As it has been mentioned previously, Malaysia, Indonesia, and Papua New Guinea, are the main world producers where sago is grown commercially for the production of sago starch and/or conversion to animal food or to ethanol. Indonesia has the largest forests of wild sago palms, in which some plants for processing sago starch and by-products has been set in Halmahera Island and in West Papua Province. However, at present time, Malaysia is the world s biggest sago starch exporter. The largest sago-growing areas in Malaysia are outside the Peninsula in the state of Sarawak, which is now the biggest exporter of sago starch, exporting annually about 25,000 40,000 tons of sago products to Peninsular Malaysia, Japan, Taiwan, Singapore, and other countries (Aziz, 2002; Singhal et al. 2007).

40 22 Currently, there are 8 sago factories operating in Sarawak, seven of which are in the Mukah-Dalat areas, and one is situated in the Igan-Sibu area (Manan et al., 2003). The modern method of extraction involves some modifications to that of the small processing plant. New technologies for extracting starch are being adopted by the large-scale factories. These factories are now fully mechanized, and that level of technology is mostly found in Sarawak Karim et al, 2008; Bujang, 2011). The commercial process which is either partially (semi-mechanized) or fully mechanized involving a sequence as presented in Figure Palm logs are rafted to the mill or factory and stored in the river to reduce deterioration (Figure 1.17). In the mill yard, the bark-like layer is stripped from each log with an axe or bush knife and the logs split into 6 8 battens which are then rasped by a diesel-powered, home-made rasping wheel which rotates at high speed. The wheel is mounted on a platform to permit the rasped pith to drop into one end of a cylindrical washing reel that rotates on a central shaft. A perforatted water pipe sprays water into the body of the reel and flushes the rasped pith as it is passed along the inside by perpendicular splines arranged in a spiral pattern along the central shaft of the reel. This loosens starch grains from the stem fiber and washes them out in suspension. Waste fibers fall from the lower end of the washing cylinder. Starch- laden water then flows through the coarse wire screen that encases the reel and is led off by a conduit through a coarse sieve which removes most of the fiber prior to sedimentation in cement tanks or wooden troughs. The starch may be separated using cyclone separators and dried on a rotary vacuum drum drier, followed by hot air drying. When dry, it is known as chong hoon. The mill extracts wet starch mechanically and produces three grades of dry starch, which, from low to high are known as chong hoon, thai hoon, and siong hoon. To produce thai hoon, the middle grade, it is sieved after drying. Crude dry

41 23 starch can be rewashed, dried again and then sieved to produce the highest grade of starch, siong hoon (Singhal et al., 2007). Sago palm logs Bark removal Bark Dry rasping of pith Wet maceration of course chips Sieving Fibre Settling and washing of starch Further purification Drying Sago starch Figure 1.15 Flow diagram of modern sago starch processing (Karim et al., 2008; Singhal et al., 2007) In some factories, the 30-cm-long sections from the storage pond are first split lengthwise into about 8 segments. These segments are fed into slicers that slice the pith from the bark. In certain other factories, the bark is first removed from sections of the logs (Figure 1.18). Each of the debarked sections, about 80 to 100 cm long, is fed into the mechanical rasper (with chrome nails mounted on 1 face of a disc or a drum) (Figure 1.19). This rasps the pith into finer pieces, which are fed into the hammer mill via a conveyor belt.

42 24 The resulting starch slurry is made to pass through a series of centrifugal sieves to separate the coarse fibers. Further purification is achieved by separation in a nozzle separator through sieve bends. A series of cyclone separators has also been used to obtain very pure starch. Dewatering of starch is carried out using a rotary vacuum drum dryer followed by hot air drying (Manan et al., 2003; Singhal et al., 2007). (a) (b) Figure 1.16 The sago trunk (a), after being felled, it is then cut into several sections, 1 to 1.2 m long (b). Figure 1.17 The sago logs are tied into rafts and transported to the plant via rivers ( photos were adapted from Bujang, 2006).

43 25 Figure 1.18 Sago logs are debarked using either an auto debarking machine or manually with a machete ( photos were adapted from Bujang, 2006). (a) (b) Figure 1.19 Rasping of debarked sago log sections to release starch granules from disintegrated fibres ( photo a was adapted from Bujang, 2006; photo b was adapted from Karim et al., 2008). Figure 1.20 Bagged sago starch ready for export ( photo was adapted from Bujang, 2006).

44 Constraints and problems of sago starch processing The main constraint of sago starch processing in Indonesia and Papua New Guinea is the method of processing that has been used. Traditional methods are still commonly practiced because of lack of mechanical equipments. The task is very labour intensive and time consuming so the starch production is very low. Consequently, both Indonesia (especially in Papua Province where 95% of Indonesian sago potential existed) and Papua New Guinea harvested the starch very small amount if compare with its potential yield. Million tons of sago starch have not harvested every year. In addition, it is suffer from low extraction rate (25% to 45%) and the starch resulted is inferior quality both in term of purity and color (Karim et al., 2008). In traditional method, pith disintegration was done using pounder, an axe-like tool, as shown previously in Figure 1.9 and During this stage of the process, close human contact with the disintegrated pith is common. In the stage, the persons (operator) are sitting on the sago trunk as they work. Not only the pounder that she used to disintegrate the pith but also their feet actively involved. This is a potential source of contamination. Unlike in Malaysia, the traditional method of extraction of sago starch has been replaced by a commercial process. However, the mechanical process that currently employed to extract sago starch is inefficient and often fails to dislodge residual starch embedded in the fibrous portion of the trunk. The amount of starch content of sago pith residue in East Malaysia alone account for nearly 50% of the total Malaysian exports of starch per year, which totals approximately 40,000 tons (Manan et al., 2001). With regard to the commercial process of sago starch, the main constraint is the transport of the boles to the factory. Each bole weighs at least 1 ton, 50% of which is moisture. Two-thirds of the boles, which float in water, are submerged. The boles are usually cut into logs measuring 1.2 m in length, which are rolled out of the planting to the

45 27 nearest waterway. In the factories area especially small factories can easily be found by the pungent smell of lactic acid fermentation. Microbial degradation and oxidative browning of phenolics of the logs are commonly occurred prior to processing. The main problem associated with sago starch processing is lost of starch in byproduct in various stages of operation. Starch losses are classified into two categories, namely: (1) Physical losses and (2) Losses of valuable characteristic due to degradation of starch. Degradation normally results in poor quality (Cecil, 1984). Physical losses of starch can occur at every stage of the process either through destruction resulting from fermentation, or by inclusion of the starch in by-product (in the bark, in the pith waste or hampas, and in the waste water. Fermentative destruction of starch caused by micro-organisms has been shown to occur in long term storage of logs as well as wet starch (lemantak). The physical losses as well as losses due to degradation of the starch related to sago starch processing are as follows (Cecil 1984): (1) Losses in bark The bark of the sago palm provides structural support for the foliage as well as protection for the soft inner part of pith. The first operation in sago starch processing is to remove this bark. Unlike bark in many species where the inside boundary of the bark is easily seen, that in sago is undefined. The outermost 5 mm of the stem is extremely hard and contains no starch. The outermost layer is very hard so it would certainly damage the rasper that is generally used; therefore it is removed. Substantial loss can occur in material left adhering to the discarded bark. Only care and attention by the barker can keep this loss to a reasonable minimum. Such inattention increased the loss of starch into the discarded bark.

46 28 (2) Rasping losses Forced feeding of pith onto the rasper results in coarser rasped pith (repos) and increased starch losses in pith waste. By careful feeding, allowing the rasper to do the work properly, thus more starch can be recovered. Gentle feeding unquestionably takes longer time. (3) Sedimentation losses Starch is separated by sedimentation from the water that carried it through the process. Sufficient sttling time is neened in the sedimentation tank for starch granules to sink to the bottom. The shallower the sedimentation tank the less is the vertical distance the granules must travel to reach the bottom. Therefore, sedimentation tanks must be relatively shallow, but to obtain the volume needed to give the necessary settling time they must have a large area. In some cases losses in table overflow is considerable, can reach 10%. (4) Losses due to degradation Most deterioration in the quality of sago starch is due to microbial action. Moisture in the starch promotes microbial damage. Water assist the action of micro-organism in two way e.g. (a) by providing essential muisture and (b) by providing a means of migration both of nutrients and of the micro-organisms themselves from one ganule to another. From the time of a sago palm is felled until the starch from it is dried, unless steps are taken to control microbial activity, damage will occur, often a a steadily increasing rate. To control the microbial activity in the field is difficult. The effects of microbial activity in stored logs, in stored repos and in stored wet starch is both obvius and insidious. Microbial damage is irreversible and irreparable. The thickness of the paste a starch makes is possibly its important characteristis. Micribial fermentation reduce the thickness of the paste the starch will produce.

47 29 In household trampling operations a whole log or a large part of a log is often rasped all at once at a contract rasper. It sometimes takes several to trample all the repos, and when it does take that long, the last of the repos shows obvious signs of fermentation, in which it smells fruity and it becomes slimy that makes it difficult to trample. Repos stored in closed containers also showed similar signs of deterioration. Fermentation is also usually associated with a fall in ph. Microbial action is accelerated by the use of untreated water for processing and by poor sanitation in processing areas. For health reasons, wet starch should always be reslurried with water containing sulphur dioxide (SO 2 ), an inexpensive wide spectrum bactericide, even if the wet starch is going to be dried immediately. The presence of fibrous material (impurity) also accelerate the degradation of wet starch. 1.6 THE OBJECTIVES OF THIS STUDY On the basis of previous studies (Darma et al., 2009; 2010 and 2011), it suggests that the existing sago starch processing equipments both sago rasper and sago starch extractor still have some limitations. Therefore, they need to be developed further. The objective of this study was to develop sago starch processing equipments in order to improve their performance. The equipments to be developed consists of two separately operation unit namely sago rasper and sago starch extractor. It is focused on the following purposes: (1) To develop cylinder type sago rasper in order to improve its performance. The focuses of this study was to investigate the effect of cylinder rotation speed and cylinder s teeth density on rasping performance. (2) To develop stirrer rotary blade type sago starch extractor in order to increase its performance, with the focuses on investigating the effect of rotary blades rotating speed and number of stationary blades on extraction performance.

48 SCOPE OF THIS STUDY The most time consuming and labor intensive stages of sago starch processing are pith disintegration and starch extraction/starch separation. For traditional method, the total time required to process one trunk is 41 hours (6 days of work) from which is 53.22% and 38.92% are respectively spent for pith disintegration and starch separation (92.14 % of the total time required) (Darma and Istalaksana, 2011). In the last ten years, several studies have been done to increase sago starch production in the farmer level in West Papua by introducing mechanical sago starch processing equipment. In previous study, a prototype of sago starch processing equipment which consists of sago rasper and sago starch extractor was resulted. Functionally, both sago rasper and sago starch extractor worked properly but they still have some drawbacks, therefore they need to be developed further to achieve a higher level of performance. The equipments were intended for small scale (household) processing of sago starch. The small scale processing of sago starch is being considered suitable to be applied in Papua and Papua New Guinea because of the distribution of sago forest in these area were very broad and mostly it grow in marginal land which difficult to access. Moreover, according to the traditional laws which are still strong in rural community in Papua and Papua New Guinea, all land belongs to the local communities and is inherited from ancestor. This is especially true where land is covered by sago palms, because sago palm plays an important role not only to provide staple food for household members but also to provide materials for building houses (roof, wall and ceiling) and bridges, as well as to maintain water conservation (Girsang, 2013, Bintoro et al., 2010). The ownership and the status of the sago forest are influenced by traditional laws and means that all community in vicinity has a right on it. Therefore, consideration must be taken so that indigenous people should be involved independently in exploitation. They should not have the status of

49 31 labors but of owner. Exploitation and processing on a large scale separate from local traditional laws is only feasible in new sago plantation resulting from new planting or reforestation and does not affect the natural sago. Based on the consideration as mentioned above, this study area focuses on development of small scale sago starch processing equipment which consists of sago rasper and sago starch extractor. This thesis document contains the results of the experiment addressed to overcome the problems facing associated with traditional sago starch processing. It is commences with introduction, followed by five consecutive research chapters concentrating on the development of cylinder type sago rasper and stirrer rotary blade sago starch extractor. The research chapters pertaining topics were as follows: (1) Development of cylinder type sago rasper for improving rasping performance (chapter 2). (2) Improvement of cylinder type sago rasper using pointed teeth (chapter 3). (3) Variant-2 of improved cylinder type sago rasper (chapter 4). (4) Development of stirrer rotary blade type sago starch extractor for improving extraction performance (chapter 5). (5) Variant-2 of Improved Stirrer Rotary Blade type sago starch Extractor (chapter 6).

50 32 CHAPTER 2. DEVELOPMENT OF CYLINDER TIPE SAGO RASPER FOR IMPROVING RASPING PERFORMANCE Rasping is the most frequently useful method to disintegrate or to break down the cellular structure of sago pith for mechanical processing. Sago palms produce starch inside pith cells. In the sago starch processing both using traditional method and mechanical method, washing is the only method that is used to extract or to separate out the starch. Unless a cell is ruptured in some way, the starch can not be washed. Therefore, the efficiency of subsequent process (starch extraction) depends on the proportion of the starch cells that are ruptured. The amount of starch obtained depends on how fine the level rasping and the efficiency of starch washed out from the rasped pulp. The more finely the pith is rasped, the more starch can be extracted in the subsequent rinsing process. In other word, in order to free as much starch as possible, the pith must be disintegrated as finest as possible. However, the rinsing process becomes more complicated in separating the starch from hampas (Cecil, 1992; Colon and Annokke, 1984). A small increase in starch yield (perhaps 3 to 5%) could be obtained with secondary rasping, but this is not practical in small operations. Further rasping gives little further increase in yield and makes separation of the starch and fibre very difficult. In addition, in large factories, hammer mills are used, but all types of mills are unsuitable (Cecil 1992). As it has mentioned previously, rasping is aimed to disintegrate or to break down the cellular structure of the pith. The are others term that commonly used synonymous with pith disintegration such as pith macerating (Greenhill, 2006) and pith pulverizing (Spade, 1999; Ellen, 2008). Meanwhile, rasping is synonymous with grating. By doing so, the starch granules which exist in the cells is freed or loosen, thus it is able to suspend into

51 33 water during extraction process. The scanning electron micrograph (SEM) of freed starch granule after the cells wall has been ruptured is depicted in Figure 2.1. Figure 2.1 Scanning Electron Micrograph of freed sago starch granules (Nitta, 2013) Rasping is the third step in sago starch processing after the trunk was felled down and debarked. Once the bark is removed, the pith is split into pieces up to 10 cm square called batons or billets. The pieces are fed onto the rasper end-on direction, the correct direction for optimal rasping (Cecil, 1992). Whatever type of rasper is used, it is important not to press the pith too forcefully onto the rasping surface, as will seriously reduce the efficiency of the rasper. In extreme cases it could overload the motor or the engine. Furthermore, forcing material onto the rasper will result in coarser repos, fewer cells will be ruptured and as a result more starch will be lost in the sago pith waste. There are two type of rasper commonly used in sago starch processing e.g. (a) Cylindrical rasper and (b) Disc rasper. The functional component of cylindrical rasper is a rotating cylinder/drum with an abrasive surface, while the disc rasper is a rotating disc with

52 34 abrasive surface. Because of its high rotation speed in the rasping process, it can cause very nasty wound, thus for safety they must be enclosed so that operator cannot get injured. The pith should be fed in through an opening that should be the whole width of the rasper, but it should be made difficult for anyone to injure a hand or foot, either accidentally or in trying to push the pith into cylinder or disc. Lumps of unrasped pith will always find their way through gaps between the rotating cylinder/disc and the housing. It is therefore important that these gaps should be kept as narrow as possible. There are some types of rasping surfaces both for cylindrical rasper and disc rasper. The simplest form of it is made from a sheet of metal perforated with nail, which has been wrapped round a wooden cylinder as well as wooden disc. It is very easy to make and nothing more than a nail and sheet of tin plate are needed for a new rasping surface, but they are inefficient. They only process a small quantity per hour and they do not last very long. Another type of rasper that is widely used and can be made locally is the nail rasper. There are various designs. Nails are held in a wooden or metal cylinder. The more nails there are, the better the rasper will work, but it is impractical to set them closer than 5 mm to one another (Cecil, 1992). The nails must be embedded in the cylinder so that they do not fly out under the considerable centrifugal forces that are produced by the high speed rotation. This type of rasper, even one with a wooden cylinder, will last a long time if it is properly made. As the nails get worn down, the wood also worn down, often at about the same rate (Figure 2.2). Every effort should be made to use the full width of the cylinder so that wear is even along its whole length. A better nail rasper is a modification of a design widely used in larger factories. Two curved plates are made from 4 mm steel plate. Each covers half of circumference of a steel or wooden cylinder 25 cm in diameter and 30 cm long. Holes just large enough for the

53 35 shafts of 15 mm long nails (preferably masonry nails) are drilled in the plates on a slightly skew square pattern, thus the nails which protrude through the plate do not exactly follow one another as the cylinder rotates. The nails are put in from the inner side and cannot go through the plate because their head are too large to pass trough the holes in the plate. The curved plates are bolted to the outside of the cylinder, which holds the nails securely in place. This rasper can be driven at 1500 rpm (Cecil, 1992). (a) (b) Figure 2.2 Cylindrical rasping surface in good condition (a) and the nails have already worn down (b) The best type of rasper is the Jahn rasper, but these are too expensive for small scale operation. It consists of a rotating cylinder on which replaceable serrated flat blades, similar to saw blades are mounted. The individual blades are made of steel about 1 mm thick and are available in different lengths such as 10, 20, and 30 cm long. They are about 2 cm wide with teeth along each long side. The saw teeth may be 2 0r 3 mm deep with the tips 1.5 to 2.5 mm apart. The blades are mounted in the plane on the axis of the cylinder. The length of the blade is parallel to the axis and the length of the working part of the cylinder is thus the same as the length of the blades. The blades are separated by wooden or metal blocks so that they are parallel and about 10 mm apart. The blocks are cut so that the teeth protrude from the surface of the blocks by 2 to 3 mm. The blocks have to be narrower on the inside (nearer the centre of the drum) than on the outside. A 30 cm

54 36 diameter cylinder having a circumference of about 100 cm will need between 70 and 100 blades, depending on the thickness of the wooden blocks. End plates with strong lips are necessary to hold the locks and saw blades against the strong centrifugal forces that will occur in the high speed rotating cylinder. When the cylinder rotates, the saw teeth are dragged sideways trough any material held against them. A 30 cm diameter cylinder can be driven at 1500 rpm and 50 cm diameter cylinder can be driven at 1200 rpm (Cecil, 1992). Modern imported rasping machine can be driven considerably faster, depending on the manufacturer s specifications. The manufacturers claim that the high speed makes them substantially more efficient, but maximum efficiency is accompanied by problems in starch separation. In addition to the various rasper as mentioned formerly, another cylinder type sago rasper that is recently used widely for small scale operation in West Papua Province, Indonesia is similar to the nail rasper (Figure 2.3). The process system of this rasper is hard wooden cylinder 15 cm in diameter and 20 cm long. The teeth are made of stainless steel rod 4 mm in diameter and 2 cm height. This rasper was driven at 3000 rpm (Darma et al., 2009; 2011). This experiment aims to develop the latter rasper in order to improve its performance. Figure 2.3 Cylinder type sago rasper that is used widely in small scale operation of sago starch processing in Papua Province, Indonesia (Darma et al., 2009).

55 Experiment materials and methods Construction of experimental sago rasper This sago rasper consisted of four main components. They are: (a) A rotating rasping cylinder covered with sharp teeth on its circumference surface enclosed in a housing made of 0.2 cm thick plate steel. The cylinder made of steel pipe is 16.8 cm in diameter and 22 cm in length (Figure 2.4). The teeth are 0.4 cm in diameter and 2 cm in height and made of stainless steel rod. There are three cylinders with different teeth density tested in this study (Figure 2.5); (b) A single phase electric motor (1.49 kw, 1490 r/min, 220 Volt) is used as power source; (c) Power from electric motor is transmitted to the cylinder by use of pulleys and V-belt; (d) Main frame is made of 0.5 cm thick equal angle (L-shape) 5 cm 5 cm steel bar. The dimension of main frame is 93 cm length, 57 cm width, and 65 cm height. In addition, it is equipped with cylinder s cover and feeding plate both made of plate steel with 2 mm in thickness. The size of feeding plate was 25 cm long and 24 cm wide. The assembly of feeding plate is mounted at a slope of 20 degrees. It is also equipped with a torque meter to measure the rasping torque requirement and tachometer to measure the cylinder rotation speed. The construction of the rasper was depicted in Figure 2.6 and 2.7. Figure 2.4 The rasping cylinder before their surface were embedded with the teeth.

56 38 (a) (b) (c) Figure 2.5 Rasping cylinder: density 1 (a), density 2 (b) and density 3 (c) Figure 2.6 Construction of sago rasper for experiment Note: (1) Rasping cylinder, (2) Feeding plate (3) Tachometer sensor, (4) Connect to sensor interface, (5) Electric motor, (6) Cylinders cover, (7) Torque meter, (8) Driven pulley, (9) V-velt, (10) Driver pulley, (11) Main frame

57 39 (a) (b) Figure 2.7 Front view (a) and side view (b) of experimental sago rasper developed in this study Experimental conditions Functional component or process system of this sago rasper is a rotating cylinder covered by sharp teeth made of stainless steel rod. The function of the cylinder was to disintegrate or break down sago pith into small particles, so that starch in the pith can be freed in subsequent steps. In order to obtain starch from the disintegrated pith, washing is the common method that is used to separate out the starch from rasped pith. If a cell has not been ruptured in some way, the starch can not be washed out. Therefore, the efficiency of extraction of the starch depends primarily on the proportion of starch cells that are ruptured. The parameters studied for rasping performance are cylinder rotation speed and teeth density on the cylinder surface. Cylinder rotation speed consists of five levels that are 745 r/min, 1490 r/min, 2235 r/min, 2980 r/min, and 3725 r/min. Adjusting cylinder rotation speed is done by changing the ratio of driver pulley (pulley on motor s shaft) to driven pulley (pulley on cylinder s shaft). Therefore, there are five different ratios of driver to driven pulleys that are used in this experiment, each corresponding to the intended rotation

58 40 speed. They are: (a) 3 inch : 6 inch, (b) 3 inch : 3 inch, (c) 4 inch : 3 inch, (d) 6 inch : 3 inch and (e) 10 inch : 4 inch. Adjusting cylinder rotation speed to an intended speed is done by changing the ratio of pulley that is being employed. The cylinder s teeth are made of stainless steel rod which is 4 mm in diameter and 20 mm in height. To set them on the cylinder surface, holes were made using electric drill, and then the teeth were firmly embedded in the cylinder. In addition, to prevent the teeth from falling away, the teeth were welded on the cylinder surface from the inner side. There were three cylinders each with different teeth densities. Density 1 is 2.2 cm 4 cm distant (4 teeth/8.8 cm 2 ), density 2 is 2 cm 3 cm distant (4 teeth/6.6 cm 2 ), and density 3 is 2.2 cm 2 cm distant (4 teeth/4.4 cm 2 ). The arrangement pattern of the teeth on cylinder s surface and the profile of teeth are shown respectively in Figure 2.8 and 2.9. Since each cylinder was subjected to five different rotation speeds therefore there were 15 experimental conditions for testing. 22 mm 40 mm Density 1 Figure 2.8a The arrangement pattern of the teeth density-1 (D1) on cylinder s circumference surface

59 41 22 mm 30 mm Density 2 Figure 2.8b The arrangement pattern of the teeth density-1 (D1) on cylinder s circumference surface 22 mm 20 mm Density 3 Figure 2.8c The arrangement pattern of the teeth density-3 (D3) on cylinder s circumference surface

60 42 β L RASPING CYLINDER Diameter : 16.8 cm Length : 22 cm Number of row : 24 Angle between row (β): 15 o Distance between row : 2.2 cm Made of 6 inch steel pipe Figure 2.9 Feature of rasping cylinder 5 mm 15 mm THE TEETH OF CYLINDER Height : 2 cm Diameter : 0.4 cm Sharp tip : 0.5 cm Made of stainless steel rod Figure 2.9 Feature of cylinder s teeth Rasping torque requirement To measure sago rasping torque requirement, the experimental rasper is equipped with torque meter (KYOWA TYPE TP-5KMCB, capacity 50 Nm) as shown in Figure 2.6

61 43 (no.7). The experimental device setting for torque measurement is illustrated in Figure Computer Amplifier and A/D converter rpm measurement Cylinder rasper Driven pulley Pillow block Torque meter V-Belt Sago pith Electric motor Driver pulley Figure 2.10 Experimental setting and instruments for torque measurement Rasping efficiency The sago palm trees (Metroxylon sago) which are ready for harvest were felled using a chainsaw. The felled sago palm trunk is then cut into shorter logs about 80 cm in length to facilitate transportation to the laboratory. The first stage in the extraction of starch is to separate the bark from the log. The bark is removed before rasping, because the bark does not contain starch and is also very hard such that it would quickly damage the cylinder s teeth. Once the bark is removed, the pith is split into square pieces suitable for the rasping process. The pieces are then fed manually onto the feeding plate and pushed gently to rotating cylinder. The pieces are fed onto rasper end-on direction (Figure 2.11). The rasped pith called repos (Cecil et al.1986; Cecil, 1992) is then collected and weighed. Rasping efficiency is defined according to Equation (1):

62 44 w R (1) t Where is rasping efficiency, kg/h; w R is weight of repos, kg; t is time required, hour. (a) Figure 2.11 Splitting and debarking sago logs (a) and sago rasping process (b) (b) Starch percentage The rasped sago pith (Figure 2.12) then was processed further using traditional method to extract starch. The starch is washed out from the repos using plenty of water. The starch was separated from fibrous and cellular residue using a fine sieve (fine cloth). In this process, repos are kneaded with water and the resulting slurry was then filtered using sieve and squeezed manually to obtain starch. The slurry passes the sieve, and then flows to the collecting tank. This process is repeated several times until virtually no starch comes out from repos. The repos containing no starch are called hampas (Cecil et al. 1986; Cecil, 1992). The starch is allowed to settle to the bottom of the collecting tank for about two hours, and subsequently the supernatant water is drained off. The wet starch in the tank is taken out and weighed. The starch percentages (wet basis) are obtained using Equation (2):

63 45 w S 100 % (2) w R Where is starch percentage, %; w is weight of starch, kg. S Figure 2.12 Rasped pith ready to be processed further to extract the starch Starch yield and power requirement Starch yield depends on rasping efficiency and starch percentage. It is obtained using Equation (3), and power requirement is obtained using Equation (4) (3) Where is starch yield, kg/hour P Tn (4) 30 Where P is power requirement, W; T is rasping torque requirement, N m; n is cylinder rotation speed, r/min. Starch yield efficiency is defined as the quotient of starch yield and power requirement. 2.2 Results and discussion Rasping torque requirement The relationship between rasping torque requirement and cylinder rotation speed of the three different cylinder s teeth densities is presented in Figure 2.13.

64 46 Rasping torque, N m Density 1 Density 2 Density Cylinder rotation speed, r/min Figure 2.13 Relationship between rasping torque requirement and cylinder rotation speed Figure 2.13 shows that the rasping torque requirement decreases with the increase of cylinder rotation speed. This decrease was due to the lower energy requirement at higher cylinder rotating speed. Darma et al. (2001) also found that rasping torque requirement to be inversely proportional to cylinder rotation speed. Rasping involves both cutting and crushing process. Sitkey (1986) stated that with the increase in cutting velocity, the energy requirements decreased considerably, and the proportion of useful cutting work increases. Sitkey (1986) further stated that cutting process may be distinguished in two stages, the first stage involves preliminary compaction of the material until a pressure is reached at which the material under the edge yield, while the second stage concerns the motion of the edge in the material. With increase in cutting velocity, preliminary compaction decreases as a result of the material s inertia and plastic behavior, whereby the energy requirements of cutting are lowered. From figure 2.13, it is also observed that higher teeth density requires higher rasping torque at the same cylinder rotating speed. Teeth density 3 has the highest torque

65 47 requirement followed by density 2 and the lowest is density 1. These results are in consistent with those of Darma et al., (2001). Higher teeth density requires higher torque because more teeth are rasping sago pith at the same time Rasping efficiency The relationship between rasping efficiency and cylinder rotation speed of three different cylinder s teeth density is shown in Figure Rasping efficiency, kg/h Density 1 Density 2 Density Cylinder rotation speed, r/min Figure 2.14 Relationship between rasping efficiency and cylinder rotation speed Figure 2.14 shows that rasping efficiency for all cylinder s teeth density increased from 745 r/min to 2235 r/min and then decreased. This increase of rasping efficiency due to rasping process at those conditions occurs rapidly, when the cylinder rotation speed is in excess of 2235 r/min, the rasping efficiency decreases. The torque of cylinder decreases while the cylinder rotation speed increases because motor s power is constant (Roth et al., 1988; Srivastava et al., 1993). In order to maintain uniform cylinder rotation speed, the speed of feeding pith onto cylinder must be reduced because pressing the pith too

66 48 forcefully reduces the rasper efficiency significantly (Cecil, 1992). On the other hand, when the power source is large enough to surpass the cutting resistance of the sago pith, increasing rotational speed of cylinder continuously increases the rasping efficiency. These results are in consistent with those of Darma at al., (2005) in which a disc type of sago rasper was tested at three different rotation speeds (700 r/min, 1400 r/min, and 2800 r/min), and Darma et al., (2009) where the same type of sago rasper was tested at three different rotation speeds (1750 r/min, 2100 r/min, and 2625 r/min). The latter experiment used almost the same size of cylinder made of hard wood but was covered by blunt end teeth and powered by using 4.1 kw (5.5 HP) gasoline engine. From Figure 2.14, it also shows that higher teeth density has lower rasping efficiency. It means that lower teeth density rasps more effectively compared with the higher density. This behavior may be related to the rasping torque requirement where the higher teeth density needs higher torque requirement and vice versa. The highest rasping efficiency for cylinder teeth density 1, density 2, and density 3 are 379 kg, 359 kg, and 255 kg per hour respectively. This is in consistent with the results by Anom (2006) which tested 2 different teeth densities (1 cm and 2 cm distance) at two rotation speeds (730 r/min and 875 r/min) Starch percentage Relationship between starch percentage and cylinder rotation speed of the three different cylinder s teeth densities is demonstrated in Figure 2.15.

67 49 30 Starch percentage, % Density 1 Density 2 Density Cylinder rotation speed, r/min Figure 2.15 Relationship between starch percentage and cylinder rotation speed Figure 2.15 shows that the starch percentage for all cylinder teeth density increased from 745 r/min to 1490 r/min and then decreased to 2235 r/min, whereas from 2235 r/min to 3725 r/min it remains approximately constant. The highest starch percentage is obtained at cylinder rotation speed of 1490 r/min. This indicates that more cellular structure of sago pith had been broken down. The pith is made of enormous numbers of cells which contains starch inside. Unless a cell is ruptured in some way, the starch cannot be washed out. Therefore the efficiency of extraction of the starch depends on a large extent on the proportion of starch cells that are ruptured (Cecil, 1992). Rasping causes rupture of cell walls and release of starch. The smaller the size of rasped pith (repos), more cell walls is ruptured therefore more starch can be obtained (Colon and Annokke, 1994). Lower starch percentage obtained at higher rotation speed of cylinder (from 2235 r/min to 3725 r/min), indicated that there are less cell walls ruptured. This is in consistent with the results by Darma et al., (2009). This is most likely related to the method of cell rupture. Manan (2011) stated that the mode of cell rupture is important for optimum starch release when water was used as a separating medium. According to Sitkey (1986), during the cutting

68 50 process various deformations occur in the material, depending on the form of cutting edge and the kinematics of the process. During cutting process, a cutting edge penetrates into a material, overcoming its strength and thereby separating it. The quality of cutting depends greatly on the knife cutting speed. For low cutting speed, the material is broken and torn by knife, and the cut section surface is not smooth. On the other hand, for high speed, the cut section surface is smoother and less deformation occurs, therefore less of cells are ruptured. Starch percentage resulted in this experiment (18% 26%) are in consistent with the results by Darma et al. (2005; 2009) ; Hermanto et al. (2011); Irawan (2007); Payung (2009); Ratnaningsih et al. (2009). It has been shown by others that starch percentage can even be more than 30% (wet basis). Darma et al. (2001; 2009; 2011) had reported that starch percentage was 30%, 31%, and 38.23% respectively. Yunus (2000) also found nearly the same value (35.45%). The amount of starch that is obtained depends greatly on the sophistication of the methods employed and starch content in the pith of sago palm. Flach (1997) reported that starch content of sago is around 10% to 25%; according to Haryanto and Pangloli (1992) and BPPT (1990), starch content in the sago pith is around 15% to 25%. Cecil (1992) also reported almost the same values (23% to 27%). Darma et al. (2010) reported that starch content of sago in Papua province varies from 12.43% to 39.89% (average 26.85%). Singhal et al. (2008) reported that starch content of the pith obtained from ready harvested sago palm varies from 18.8 % and 38.8% (fresh weight basis). It is also shown in Figure 2.15 that higher starch percentage is obtained at experimental condition of lower teeth density. The highest starch percentage (26.44%) was achieved at density 1 with cylinder rotation speed of 1490 r/min while at the same rotation speed starch percentage is 26.22% which is near to the peak value of 26.44% at the experimental condition of teeth density 2. The lowest starch percentage in this experiment

69 51 was 18% obtained at the experimental condition of teeth density 1 at cylinder rotation speed of 745 r/min. These results indicate that pith disintegration at cylinder s teeth density 1 was better compared with cylinder s teeth density 2 and density 3. This is likely related to the rasping effectiveness where cylinder with high teeth density rasp less effective compared to that with the low teeth density cylinder. These results are in contrary with that by Darma et al. (2001). This is also in contrary with that of Manan (2011). Payung (2009) tested a disc rasper with three different teeth densities and also found that starch percentage is high using the rasper with higher teeth density disc. The different results of starch percentage among researchers indicate that not only the teeth density but also height, diameter, and geometry of the teeth affect starch percentage Starch yield and power requirement Starch yield depends on both rasping efficiency and starch percentage. The relationship between starch yield and cylinder rotation speed and corresponding rasping power requirement of three different cylinder s teeth density is shown in Figure Starch yield, kg/hour Density Density 2 Density 3 Density Density 2 Density Cylinder rotation speed, r/min Rasping power requirement, kw.h Figure 2.16 Relationship between Starch yield and cylinder rotation speed (solid line) and corresponding rasping power requirement (dash line)

70 52 Figure 2.16 shows that starch yield initially increases with the increase of cylinder rotation speed from 745 r/min to 2235 r/min and then decreases. The increase in starch yield from 745 r/min to 2235 r/min is due to the increase in both rasping efficiency and starch percentage, whereas the decrease of starch yield from 2235 r/min to 3725 r/min is due to a decrease of rasping efficiency (as is shown in Figure 6) while starch percentage remains nearly constant (as is shown in Figure 2.8). A higher starch yield is obtained at lower cylinder s teeth density, and is related to the rasping efficiency and starch percentage. The highest starch yield (84.96 kg/hour) was achieved at teeth density 1 with cylinder rotation speed at 2235 r/min, then teeth density 2 with cylinder rotation speed at 2235 r/min (82. kg/hour), then teeth density 2 with cylinder rotation speed at 1490 r/min (81 kg/hour), and the lowest was kg/hour achieved at teeth density 3 with cylinder rotation speed at 745 r/min. Starch yield varied quite considerably between researchers depending on the sophistication of the method applied and the starch content of sago pith. The highest starch yield that was obtained in this experiment was lower compared with those Darma (2009; 2011) and Yunus (2000) which had found starch yields of respectively kg/hour, kg/hour and kg/hour. The reason is that the researchers used a larger power source to drive the cylinder rasping (4.1 kw). Payung (2009) and Ratnaningsih (2009) also used a 5.5 hp gasoline engine to drive the rasper and found that starch yields were kg/hour and kg/hour respectively, which are lower compared with the results of this experiment. Figure 2.9 also shows that rasping power requirements vary according to cylinder rotation speed and teeth density. The rasping power requirement increases with an increase of cylinder rotation speed. Rasper with cylinder s teeth density 3 has the higher rasping power requirement followed by that with cylinder s teeth density 2 and cylinder s teeth density 1. It means that the higher the teeth density, the higher the rasping power

71 53 requirement. The most promising experimental conditions are teeth density 1 and density 2 at cylinder rotation speed of 2235 r/min, and teeth density 2 at cylinder rotation speed of 1490 r/min. In the three conditions the starch yield efficiency was kg/kwh, kg/kwh and 92 kg/kwh respectively. The highest starch yield efficiency was obtained at the condition of teeth density 2 with cylinder rotation speed of 1490 r/min. 2.3 Conclusions From this study, a cylinder type of sago rasper using a metal cylinder covered with sharp pointed teeth on its surface has been developed. In the rasping experiments, five different speeds of cylinder rotation (745 r/min, 1490 r/min, 2235 r/min, 2980 r/min, and 3725 r/min) and three densities of cylinder s teeth (2.2 cm 2 cm, 2.2 cm 3 cm, and cm) were examined. The developed sago rasper works properly and has high performance. From this experiment it is concluded as follows: (1) Cylinder type sago rasper with different teeth density developed in this study could be used in sago rasping process. (2) The higher the cylinder s teeth density the larger the rasping torque requirement, while the higher the cylinder rotation speed, the smaller the rasping torque requirement. (3) Rasping efficiency increases from 745 r/min to 2235 r/min and then decreases continuously to 3725 r/min. The highest rasping efficiency ( kg/hour) is achieved under experimental condition at teeth density 1 with cylinder rotation speed of 2235 r/min. (4) Starch percentage increases with the increase of cylinder rotation speed from 745 r/min to 1490 r/min and then decreases to 2235 r/min. Further increase of cylinder rotation speed results in a relatively constant starch percentage. The highest starch percentage (26.44%) is achieved at experimental condition at teeth density 1 with cylinder rotation speed at 1490 r/min.

72 54 (5) Starch yield increases from 745 r/min to 2235 r/min and then decreases continuously to 3725 r/min. The highest starch yield (84.94 kg/hour) is achieved under the experimental condition with teeth density 1 at cylinder rotation speed of 2235 r/min. (6) The most promising experimental conditions are teeth density 1 and density 2 at cylinder rotation speed of 2235 r/min, and teeth density 2 at cylinder rotation speed of 1490 r/min. In the three conditions the starch yield efficiency was kg/kwh, kg/kwh and 92 kg/kwh respectively. The highest starch yield efficiency was obtained at the condition of teeth density 2 with cylinder rotation speed of 1490 r/min.

73 55 CHAPTER 3. IMPROVEMENT OF CYLINDER TYPE SAGO RASPER USING POINTED TEETH Previous experiment (as discussed in chapter 2) was intended to investigate the effects of cylinder rotation speed and teeth density on rasping performance as well as rasping torque requirement. Based on previous experiment results suggested that developed cylinder type sago rasper works properly and has high performance compared with existing prototype which using blunt teeth. Therefore it was able to be used as a basic form to develop further in actual size. Principally, this experiment was similar to previous experiment, but differs only in the power source which is used and the frame was simpler because not equipped with torque meter device. This experiment purposes to develop further the sago rasper that has been developed in previous experiment. Unlike with previous experiment which is driven by 2 hp electric motor, in this experiment it is driven by 6.5 HP gasoline engine. Meanwhile, the teeth and cylinder was identical. 3.1 Experiment materials and methods Construction of sago rasper The rasper also consists of 4 main components, they are: (a) A rotating rasping cylinder covered with sharp teeth on its circumference surface enclosed in a housing made of plat steel. The cylinder is identical with those of previous experiment (b) 4-stroke gasoline engine (6.5 hp, maximum shaft rotation 3600 rpm) is used as power driver, (c) Power is transmitted by the components of pulley and V-belt, (d) Main frame is made of 5 cm x 0.5 cm equal angle steel bar. In addition, it is equipped with cylinder s cover and

74 56 feeding component both made of plat steel with 2 mm in thickness. The sago rasper improved in this study is presented in Figure Note: 1.Cylinder s cover 2.Cylinder rasper 3. Feeding input plate 4. Main frame 5. Engine 6. Driven pulley 7. V-belt 8. Driver pulley Figure 3.1 Construction of cylinder type sago rasper powered by 6.5 hp gasoline engine Experimental conditions Similar to the previous experiment, the parameters studied for improving rasping performance were cylinder rotation speed and teeth density on the surface of cylinder. Cylinder rotation speed consists of 3 levels i.e rpm, 2250 rpm, and 3000 rpm. Adjusting cylinder rotation speed is done by changing the ratio of driver pulley (pulley on motor s shaft) to driven pulley (pulley on cylinder s shaft). Therefore, there are 3 different ratios of driver to driven pulleys that are used in this experiment, each corresponding to the intended rotation speed. The ratios of pulley that have been employed are 3 inch: 6 inch, 3 inch: 4 inch and 3 inch: 3 inch; Each corresponding to the cylinder rotation speed of 1500 rpm, 2250 rpm and 3000 rpm respectively.

75 57 The features of rasping cylinder and the cylinder s teeth are same with those of previous experiment. There were 3 cylinders each with different teeth densities. Teeth density 1 (D1) was set at 2.2 cm 4 cm apart, density 2 (D2) was 2.2 cm 3 cm, and density 3 (D3) was 2.2 cm 2 cm (Figure 3.2). The arrangement pattern of teeth on the surface of cylinder is identical to those of previous experiment. Since each cylinder was subjected to the three different rotation speeds, thus there were 9 experimental conditions for test. D1 D2 D3 Figure 3.2 The Rasping cylinder of D1, D2, and D Rasping efficiency Procedure and the steps for rasping efficiency measurement are same with previous experiment. However, because of the power driven is being used much bigger (3.5 times bigger), more sago pith was needed for rasping efficiency test. After a sago palm tree is cut down, it is then cut into logs about 1.0 m long (Figure 3.3) and transported to the processing site. Before rasping, the logs are debarking or removing the bark by using chain saw (Figure 3.4). Once the bark is removed, the pith is split lengthways into pieces up to about 10 cm square which are suitable for the rasping process. Rasping is conducted by

76 58 pressing manually the pith pieces against rotating rasping cylinder. The rasped sago pith is then collected and weighed. Rasping efficiency is defined according to equation (3.1): w R (3.1) t Where is rasping efficiency, kg/h; w R is weight of repos, kg; t is time required, hour. a b Figure 3.3 Cutting the sago trunk into logs (a) and the logs ready to transport (b) a b Figure 3.4 Debarking and splitting the logs before rasping (a) and sago rasping process (b)

77 Starch percentage The aim of sago processing is to extract starch from the sago logs. The amount of starch that is obtained depend on the fineness of rasped pith (repos) in which affected by rasping cylinder s teeth density and the efficiency of starch separation/starch extraction. The starch was separated from fibrous and cellular residue using stirrer rotary blade sago starch extractor (Figure 3.5a). In this process, repos is suspended in water and then stirred rigorously to release the starch. The suspended starch or starch slurry is then separated from the repos using a screen, and is then flow to the collecting/sedimentation tank. The starch is allowed to settle to the bottom of the collecting tank for about 1 to 2 hours, and subsequently the supernatant water is drained off. The wet starch in the tank is taken out and weighed (Figure 3.5b). The starch percentages (wet/fresh starch) are obtained using equation (3.2): w S 100 % (3.2) w R Where is starch percentage (%); w is weight of starch (kg). S Starch yield Starch yield is the total amount of starch resulted per unit of time. It depends on rasping efficiency and starch percentage, and is obtained using equation (3.3): R (3.3) C Where is starch yield (kg/hour)

78 60 (a) Figure 3.5 Starch extraction using stirrer rotary blade sago starch extraction (a) and wet sago starch ready to weighed (b) (b) 3.2 Results and Discussion Rasping efficiency The relationship between rasping efficiency and cylinder rotation speed of 3 different cylinder s teeth density is shown in Figure 3.6. Rasping efficiency (kg/hour) Density 1 (D1) Density 2 (D2) Density 3 (D3) Cylinder rotation speed (rpm) Figure 3.6 Relationship between rasping efficiency and cylinder rotation speed

79 61 Figure 3.6 shows that rasping efficiency for all cylinder s teeth density increased from 1500 rpm to 2250 rpm and then decreased. This increase of rasping efficiency was due to the rasping process at those conditions occurs rapidly. On the other hand, as the cylinder rotation speed is excess of 2250 rpm, the rasping efficiency decreases. This behavior was related to the torque magnitude available on the rasping cylinder. The higher the cylinder rotation speed, the lower the torque on it, as driver s power from engine is constant. Theoretically, in any power transmission system, torque is inversely proportional to the rotation speed (Roth et al. (1988) and Srivastava et al (1993). This is consistent with previous experiment (chapter 2). These results are also consistent with those of Darma (2005) in which a disc type of sago rasper was tested at 3 different rotation speeds (700 rpm, 1400 rpm, and 2800 rpm), and Darma (2009) where the same type of sago rasper was tested at 3 different rotation speeds (1750 rpm, 2100 rpm, and 2625 rpm). The latter experiment used almost the same size of cylinder made of hard wood but was covered by blunt end teeth and powered by using 5.5 HP gasoline engine. Furthermore, as it is shown in Figure 3.6, higher teeth density has the lower rasping efficiency. It implies that lower teeth density rasps more effectively compared with the higher density. Rasping torque requirement of higher teeth density is bigger than the lower teeth density, as a result rasping process occurs slowly. On the other hand, because of its lower rasping torque requirement of the lower teeth density, rasping process take place rapidly, therefore rasping efficiency is higher. Previous experiment (as discussed in chapter 2) revealed that the higher the teeth density, the lower the rasping torque requirement. The highest rasping efficiency for cylinder s teeth density 1, density 2, and density 3 are 1009 kg, 960 kg, and 730 kg per hour respectively. These results are considerable higher compared with previously study as discussed in chapter 2.

80 Starch percentage Relationship between starch percentage and cylinder rotation speed of the 3 different cylinder s teeth densities was shown in Figure Starch percentage (%) Density 1 (D1) Density 2 (D2) Density 3 (D3) Cylinder rotation speed (rpm) Figure 3.7 Relationship between starch percentage and cylinder rotation speed Figure 3.7 shows that the starch percentage for all cylinder teeth density nearly constant from 1500 rpm to 2250 rpm and then slightly increase to 3000 rpm. The highest starch percentage is obtained at teeth density 1 (D1) with cylinder rotation speed at 3000 rpm. This indicates that more cellular structure of sago pith which contains sago starch granules had been broken down at the condition. These results slightly inconsistent to the previous experiment in which shown that starch percentage resulted from 2235 rpm to 3725 rpm were almost constant. These results probably related to the higher power driven have been used in the latter experiment. Starch percentage resulted in this experiment (44.34 % %) were considerably higher compared to the previous experiment. These results also higher compared to those of Darma (2005; 2009) ; Hermanto et al. (2011); Irawan (2007); Payung (2009); Ratnaningsih et al. (2009). The higher starch percentage obtained in this experiment was

81 63 due to the high starch content of sago pith that has been processed. The amount of starch that is obtained depends greatly on the sophistication of the methods employed and starch content in the pith of sago palm. Different trunk contains different portions of both moisture and starch. The starch content in the pith depends on a number of factors. The variation in the yield of sago palm has been attributed to biophysical difference or difference in management technique and as result of differential skill and technology (Rakha, 2004). In very good trunks there may be as much as 40% of starch in the pith, but an average of between 30% and 35% (Cecil, 1992) Starch yield Figure 3.8 shows the relationship between starch yield and cylinder rotation of 3 different cylinder s teeth density. 600 Starch yield (kg/hour) Density 1 (D1) Density 2 (D2) Density 3 (D3) Cylinder rotation speed (rpm) Figure 3.8 Relationship between starch yield and cylinder rotation speed As shown in Figure 3.8, starch yield initially increases with the increase of cylinder rotation speed from 1500 rpm to 2250 rpm and then decreases. The increase in starch yield

82 64 from 1500 rpm to 2250 rpm was due to the increase of rasping efficiency while the starch percentage almost constant, whereas the decrease of starch yield from 2250 rpm to 3000 rpm was due to a decrease of rasping efficiency (as shown in Figure 3.6) even though starch percentage slightly increase (as shown in Figure 3.7). The higher starch yield is obtained at lower cylinder s teeth density, and it is related to the rasping efficiency and starch percentage. Highest starch yield (476 kg/hour) was obtained at teeth density 1 (D1) with cylinder rotation speed of 2250 rpm, followed by teeth density 2 (D2) with cylinder rotation speed of 2250 rpm (439 kg/hour), and the lowest was 267 kg/hour obtained at teeth density 3 (D3) with cylinder rotation speed of 1500 rpm. It indicates that the higher the teeth density the lower the starch yields. These results trend were consistent with previous study (as discussed in chapter 2). However, due to the larger power driver have been used in this experiment, the starch yield obtained was higher. 3.3 Conclusions The improved sago rasper resulted in this study works properly and has high performance. The best experimental condition to produce highest rasping efficiency as well as starch yield was teeth density 2.2 cm x 4 cm with cylinder rotation speed of 2250 rpm. In the condition the rasping efficiency and the starch yield were 1009 kg/hour and 476 kg/hour respectively.

83 65 CHAPTER 4. VARIANT-2 OF IMPROVED CYLINDER TYPE SAGO RASPER As mentioned formerly in chapter 2, recently the existing sago rasper that is widely used for household operation in West Papua Province, Indonesia is cylinder type with blunt teeth (Figure 4.1). The process system of this rasper is hard wooden cylinder 15 cm in diameter and 20 cm long. The teeth are made of stainless steel rod 4 mm in diameter and 2 cm height. This rasper was driven at 3000 rpm by 5.5 hp gasoline engine (Darma et al., 2009; 2011). The final goal of the whole experiment conducted in this study is to produce the most suitable sago starch processing equipments both rasper and starch extractor. Not only in term of technical aspects but also economic and socio-cultural aspects of the equipments have to be considered. In order to provide more information on the variations of starch yield obtained at different magnitude of power source, the improved sago rasper need to be tested using 5.5 hp engine. This experiment aims to investigate the rasping performance of teeth density 1 (D1), density 2 (D2) and density 3 (D3) when they driven with 5.5 hp gasoline engine. Based on the existing rasper which is driven with 5.5 hp engine at 3000 rpm, this experiment also use the same engine at the same rotation speed. In general, this experiment was same to the previous experiment (as described in chapter 3), except for the power source which is used.

84 66 Figure 4.1 Existing sago rasper that is recently used in West Papua, Indonesia 4.1 Experiment materials and methods Construction of sago rasper Overall, the construction of this rasper is same as those of in chapter 3, but the only difference is the power driver is being used. In this experiment, the rasping cylinder was driven with a 5.5 hp gasoline engine instead of 6.5 hp (Figure 4.2). Figure 4.2 Construction of cylinder type sago rasper powered by 5.5 hp gasoline engine

85 Experimental conditions Unlike previous experiment as described in chapter 3, the parameters studied for improving rasping performance was only teeth density on the cylinder s surface. Like as previous experiment, there were three teeth density to be examined e.g. density 1 (D1), density 2 (D2) and density 3 (D3) which were identical to those of chapter 3. Meanwhile, the cylinder rotation speed was set at 3000 rpm. As each teeth density was subjected only to the rotation speed of 3000 rpm, thus there were 3 experimental conditions for test. The ratios of driver pulley to driven pulley that have been used are 4 inch: 4 inch. In addition, for a comparison, it was also tested the existing rasper. D1 D2 D3 Figure 4.3 The Rasping cylinder of D1, D2, and D Rasping efficiency Procedure and the steps for rasping efficiency measurement as well as the formula is being used are same with those of described in chapter Starch percentage Procedures and steps are same as previous experiment (chapter 3).

86 Starch yield Starch yield measurement uses the same procedures as previous experiment (as described in chapter 3). 4.2 Results and Discussion Rasping efficiency Figure 4.4. Rasping efficiency of various teeth density as and existing rasper was displayed in Rasping efficiency (kg/hour) D1 D2 D3 ER Teeth density Figure 4.4 Rasping efficiency at teeth density D1, D3, D3 and ER * ( *: is existing rasping cylinder as shown in Figure 4.1). Figure 4.4 shows that the higher the density of the teeth the lower the rasping efficiency. It is indicate that lower teeth density rasps the sago pith more effectively compared with the higher teeth density. This result is consistent with these of previous experiment (chapter 2 and 3). As it was explained formerly in chapter 2 and 3, lower teeth density needs lower rasping torque requirement, therefore, rasping process occurs faster and vice versa. Compared to the existing rasper, the rasping efficiency of density 1 (D1) and density 2 (D2) are higher, while density 3 (D3) is lower. The highest rasping

87 69 efficiency is obtained at the condition of teeth density 1 (635 kg/hour) followed by density 2 (589 kg/hour), existing rasper (533 kg/hour) and the lowest is density 3 (428 kg/hour) Starch percentage The starch percentage of the pith at three teeth density as well as existing rasper (ER) was shown in Figure Starch percentage (%) D1 D2 D3 ER Teeth density Figure 4.5 Starch percentage at teeth density D1, D3, D3 and ER * ( *: is existing rasping cylinder as shown in Figure 4.1). As can be seen in Figure 4.5, the starch percentage was almost the same for all teeth density. This result was consistent with previous experiment (chapter 2 and 3) which showed that no different starch percentage at the cylinder rotation speed of 3000 rpm. This is also true when the cylinder rotation speed exceed 3000 rpm. The starch percentage obtained in this experiment (22.4% %) was almost similar to the previous experiment (chapter 2), however, compared to the previous experiment (chapter 3), this results were about twice lower. The starch percentage resulted in previous experiment as discussed in chapter 3 were % %. This difference was due to the variation of starch content of sago trunk have been used in the experiment.

88 Starch yield The starch yield resulted from different teeth density of rasping cylinder was shown in Figure 4.6. Starch yield (kg/haour) D1 D2 D3 ER Teeth density Figure 4.6 starch yield at teeth density D1, D3, D3 and ER * ( *: is existing rasping cylinder as shown in Figure 4.1). As observed in Figure 4.6, higher starch yield was obtained at lower teeth density. This trend was same as previous experiment (chapter 2 and 3) when the cylinder rotation speeds at 3000 rpm. However, the starch yields were considerable lower compared to those of experiment (chapter 3) because of starch content in the pith was lower. In addition, the power rate is being used was smaller. The power rate has significant effect on rasping efficiency and so starch yield. The larger the power rate, the higher the starch yield resulted. Compared to the existing rasper (ER), the starch yield obtained at the teeth density D1 (142 kg/hour) and D2 (132 kg/hour) were higher. Meanwhile, the starch yield obtained at D3 was lower compared to the ER. It implies that both D1 and D2 have the higher rasping performance than ER.

89 Conclusions In general, Variant-2 of cylinder type sago rasper resulted in this experiment has higher performance compared to the existing rasper. The highest rasping performance was obtained at the experimental condition of teeth density 1 (D1) followed by density 2 (D2) and the lowest was density 3 (D3). The rasping performance were rasping efficiency 635 kg/hour, starch percentage % and starch yield 142 kg/hour.

90 72 CHAPTER 5. DEVELOPMENT OF SAGO STARCH EXTRACTOR WITH STIRRER ROTARY BLADE FOR IMPROVING EXTRACTION PERFORMANCE To free the sago starch, pith must be disintegrated or pulverized, mostly using rasper. It is well known that the better the pith is disintegrated, the higher the yield of starch is. On the other hand, at a high degree of disintegration, also fibre is disintegrated to appreciable extent which gives rise to trouble in subsequent fibre-starch separation (starch extraction) (Colon and Annokke, 1984; Cecil, 1992). After rasping, starch and fibre are in a free state and are able to be separated in the extraction process. The objective of the extraction process is to remove maximum amount of fibre possible from the starch and to obtain the maximum amount of starch. The efficiency of the extraction depends on how carefully the operation is managed. Up to the present time, the only way to separate starch from the fibre (starch extraction) is by assistance of water. The freed starch which is contained in the rasped pith (repos) is washed out using a plenty of water. The principles of starch extraction are to suspend or to dissolve the starch into water and then stirred rigorously to release the starch. The suspended starch or starch slurry is then separated from the fibre using a screen. Screening is the main operation in starch separation. The purpose of screening is to separate starch from fibre and other constituents. The fractions are separated by size by washing the rasped pith on a screen or a series of screens. Screening is often done in two stages, a coarse screening operation to remove most of the fibre and to thoroughly wash the starch out of it and a fine screening operation to separate fine fibre from the starch. Soluble materials such as sugars, some of the protein, and many of the other constituents

91 73 are dissolved and pass through the screen along with the fine insoluble materials (starch granules and fine fibre) (Cecil, 1992). A good screening operation should wash starch as much as possible through the screen with as little water as possible. A screen with large apertures will have a large capacity but it will allow the passage of too much oversized material. On the other hand, a screen with small apertures will give a better result, but its capacity will be smaller. Use of a screen with apertures of mixed sizes gives the worst result. In this case, the largest apertures will largely determine the quality of what passes trough, but the smaller apertures may contribute to the capacity of the screen. It is best if all apertures are the same size. Fine cloth is commonly used as screen material in traditional method of starch extraction (Figure 5.1) and sometimes it made from the fibrous leaf sheath of either coconut or sago palm (Figure 5.2). Another important physical aspect of a screen is the total open area of the holes. Both solids and liquids can only pass between the strands, thus the more bulky the strands are, the less open area there can be for product to pass through. Natural fibres are relatively short and in order to make a long strong thread they have to be twisted together in bundle. This makes the strands comparatively bulky and there are always loose hairs that restrict the passage of particles trough nearby apertures. Syntetics can be made in strong single strands which are fine and smooth and cause the least possible restriction to the passage of starch and water. It is also much easier to keep synthetic cloth clean than it is with made from natural fibres. The screens work best if the cloth is tight. Syntetic cloth elongates when it is wet, thus before putting it on the screen frames, the cloth should be soaked in water. The choice of screening technology to be used in a starch processing plan depends on a number of factors, including availability of water, availability of labour and settling tanks.

92 74 Figure 5.1. Screen material made of fine cloth Figure 5.2. Screen material made of fibrous leaf sheath of coconut Coarse screening At present time, there are two suitable designs for the coarse screening operation, namely: (a) Rotating screen and (b) Flat vibrating (shaking) screen. A rotating screen is much more expensive and more difficult to install, but it is much easier to operate once it is installed. At the small scale of operation, a coarse mesh flat screen is recommended (Cecil, 1992).

93 75 (a) The shaking screen. The weigh of pulp that can accumulate on a flat screen can quickly stretch the cloth, reducing its ability to discharge the washed pulp, so shaking screen should slope sufficiently to keep the weight of pulp on them and the screen material must be well supported. The screen can be shaken by hand or shaken mechanically at about 200 oscillations per minute with an eccentric drive. Sprays of water should be directed onto the pulp to wash out all of the fine materials. The size of the screen depends on a number of factors, such as aperture size, the fineness of the rasping, the fiber content of the pith and the frequency of oscillations (Cecil, 1992). (b) The shaking screen. In rather larger factories, rotating screens are almost always used. Six rectangular frames holding the cloth are joined together along their long sides to form an open ended cylinder with hexagonal cross-section. The frame is mounted on the rollers of which is driven. The assembly is mounted at a slight slope (about 5%) so that pulp which is introduced at the higher end gradually moves down to the lower, outlet end. The screen rotates around its long axis at 15 to 20 rpm (Cecil, 1992). Water is sprayed onto the pulp from a pipe inside the cylinder. Water is also sprayed onto and through the mesh at the top of its travel to keep the screen clean. The starch and fine pulp material is washed through the screens (Figure 5.3 and 5.4). Fine screening The starch suspension/starch slurry flowing from the coarse screen contains not only starch but also fine fibre and others soluble materials. Shaking flat screens are usually used for the fine screening operation. Normally cloth with a maximum aperture of 125

94 76 microns gives a satisfactory product, but 100 micron cloth (with a much smaller capacity per square meter) gives a better quality starch. The screen size is about 1 m long and 50 cm wide and is best shaken with an eccentric drive at about 200 oscillations per minute. Figure 5.3 A rotating sago starch screen (photo was taken from Badan Pengkajian dan Penerapan Teknologi, BPPT,1990) Figure 5.4. Integrated Sago Processing Machine (Indonesia Agency for Agricultural Research and Development, IAARD, 2001).

95 77 In addition to the rotating screening and shaking screening, Darma et al., (2010; 2011) have used new type of sago starch separation called stirrer rotary blade sago starch extractor (Figure 5.5 and 5.6). It consists of a cylinder with screen at the bottom of the cylinder. To release the starch granules from fibre, the pulp was stirrer rigorously using stirrer blade. Unlike rotating screening in which the screen is rotate as it operates, the screen of this extractor is neither rotating nor shaking. It is mounted fixedly at the bottom of the cylinder. In principle, this extractor is similar to the traditional one, but instead of using either hand or foot to knead or to trample the pulp, the pulp is kneaded mechanically using stirrer. In general, it works properly and has a good performance. However it still has some drawbacks that have to be overcome. The objective of this experiment was to develop the stirrer rotary blade sago starch extractor in order to improve its performance. Figure 5.5 Stirrer rotary blade sago starch extractor (Darma et al., 2010).

96 78 Figure 5.6 Stirrer rotary blade sago starch extractor (Darma et al., 2011). 5.1 Experiment materials and methods Overall structure and operating principles After pith disintegration, which aims to break down cellular structure and to rupture the cell walls, fiber and starch existed in the repos have not separated yet. The function of this extractor was to separate starch from fibre (pith waste). In doing so, the rasped pith (disintegrated pith) and water were fed into the extraction cylinder and then stirred rigorously. The separation of the starch granules from the fibre, so far can only be removed by a washing process using water. The starch separation mechanism is combination of kneading and screening. Firstly, rasped pith (repos) is suspended in water and then stirred rigorously to release the starch. The suspended starch or starch slurry is separated from the fibre using a screen. Starch suspension that passes through the screen is then flowed to the settling tank using a pipe. This sago starch extractor consists of several main components which are integrated in a single operational system (Figure 5.7). The extractor has the following features: (1)

97 79 Extraction cylinder, made of 2 mm thick steel. The cylinder s size was 74 cm in diameter and 120 cm in height (volume = 0,544 m 3 ). The lower end of the cylinder was a conical shape to prevent starch sedimentation incidence in the bottom of cylinder; (2) A screen, made of perforated stainless steel sheet with the holes size of 1.5 mm in diameter. The screen s diameter is slightly smaller than extraction cylinder and it is placed inside the extraction cylinder; (3) Stationary blades are made of 5 mm thick L-shape 50 mm x 50 mm steel bar. They are mounted vertically on the inner surface of screen; (4) Stirrer rotary blades, its function are to free starch granule from fiber and suspended into water; (5) Power transmission system, consists of v-belt, pulley and reduction gear box (WPX 80, ratio 10:1); (6) Power source, using a 6.5 HP gasoline engine; (7) Frame is made of 5 cm 0.5 cm equal angle steel bar. In addition, it is equipped with a pipe (2 inch in diameter) to pass starch suspension from extraction cylinder to the sedimentation tank. At the end of the pipe, it is equipped with a stop tap (valve) to control starch suspension flowing. More over, because of some fine fibre were also passed through the screen along with starch, thus it needs to be screened further to discard the fine fibre. For this purposes, a second screen which is made of fine cloth was used and it was placed at the end of flowing pipe (Figure 5.7). Starch suspension from the extraction cylinder was passed through this second screen before flow to the sedimentation tank.

98 Note: (1) Reduction gear box, (2) Extraction cylinder, (3) Gate, (4) Driven pulley, (5) Fastener pulley, (6) Engine, (7) Frame, (8) Flowing pipe, (9) Valve, (10) Fine cloth sieve, (11) Starch suspension, (12) Collecting tank. Figure 5.7 Overall structure of stirrer rotary blades sago starch extractor Experimental conditions The processes of starch extraction which occur in the extractor involve stirring and screening (filtering) simultaneously. In order to hasten the filtering process, it is necessary to create turbulent current of starch suspension inside the extraction cylinder (Figure 5.8). For this purpose, the inner surface of the screener was equipped with stationary blades. During the stirring process, starch granules are suspended in the water and forced pass through the pores of the screener. The functional parts of this extractor are screener (Figure 5.9) and the stirrer rotary blades. Previous research (Darma et al., 2010) has shown that as stirrer blades rotation speed increases, extraction rate increases. The extraction performance was tested under experimental conditions as follows: (1) Rotating speed of stirrer rotary blades consisting of 3 levels i.e. 100 rpm, 150 rpm and 200 rpm. (2) Number of stationary blades consisting of

99 81 4 different numbers (four levels): no blades, 4 blades, 8 blades and 12 blades. Adjustment of stirrer rotary blades rotating speed is conducted by changing the ratio of the driver pulley (pulley on motor s shaft) to driven pulley (pulley on gear box input shaft). Therefore, there were three different ratios of driver to driven pulleys were used in this experiment, each corresponding to the intended rotation speed. The rotation speed on engine s shaft was set at 3000 rpm and reduction gear box is being used has the ratio of 10:1, thus the ratio of driver pulley to driven pulley were 3 inch : 9 inch, 3 inch : 6 inch and 6 inch : 9 inch. (a) (b) Figure 5.8 Screener was ready to be assembled (a) and it already to be mounted in the extraction cylinder (b) Note: (1) Reduction gear box, (2) Screener/sieve, (3) Shaft of rotating blade, (4) Stationary blade, (5) Rotating blade (6) Rasped pith (repos) with water in extraction cylinder (pulp) Figure 5.9 Functional components of the extractor

100 Extraction efficiency measurement The process flow of the extraction operation that has been conducted in this research is shown in Figure As mentioned previously, it is necessary to rupture cell walls in order to release the starch granules. Unless the cells are ruptured in some way the starch can not be washed out in the extraction process. For this purpose, the sago pith was broken down using a rasper. The sago rasper which was used in this study was cylinder type with sharp teeth (Darma et al., 2013). Sago palm trunk Logs Debarking and splitting Bark Rasping Starch extraction Hampas Starch sedimentation Re-extract Dewatering Starch left in hampas Wet starch Starch drying Figure 5.10 Overall process flow chart of sago starch processing

101 83 The extraction of starch starts by feeding the rasped pith (repos) manually into the extraction cylinder (Figure 5.11b). As much as 90 kg of repos was fed into the extraction cylinder in each procedure. Water is also being added and constantly supplied into the machine while the extraction process is occurring to facilitate starch extraction. The stirrer rotary blade rotated at a fixed speed according to its designation speed as mentioned previously in experimental conditions (sub section 5.1.3). While the stirring process is taking place, starch granules are forced to pass through the pores of screener into the outer surface where they then flowed to the sedimentation tank via pipe. This process was stopped when all starch had been washed out (no more starch in the repos), which was indicated by the slurry draining out from the extractor becoming clear. The time needed from the beginning to the end of extraction process was recorded. Extraction efficiency was then determined according to equation (5.1): w E R e t (5.1) Where E e is extraction efficiency (kg/hour); wr is weight of repos (kg); t is time required (hour). (a) (b) Figure 5.11 Rasped pith ready to be processed (a) and input the rasped pith into the extractor (b)

102 Starch percentage and starch yield measurement The resulting starch suspension in the collecting/settle tank was left for sedimentation to allow starch particle to precipitate at the bottom of tank. Meanwhile, sago pith waste (hampas) which is retained in the extractor was discarded out at the extractor gate (Figure 5.12). After 2 hours, supernatant water was drained out and the fresh or wet starch was taken and weighed (Figure 5.13 and 5.14). Figure 5.12 Sago pith waste (hampas) was discarded out manually from extractor (a) (b) Figure Supernatant water was drained out (a) and fresh starch was taken out and then weighed (b) The starch percentage (wet basis) was obtained using equation (5.2) and starch yield was obtained using equation (5.3). w w S R 100 % (5.2)

103 85 (kg/hour). E (5.3) r Where is starch percentage (%); w is weight of starch (kg); is starch yield S STARCH SUSPENSION STARCH WATER STARCH (a) (b) (c) WATER WAS DARAINED OUT Figure 5.14 Starch suspensions in sedimentation tank (a), after 2 hours starch was settled at the bottom of the tank (b), then supernatant water was drained out and fresh starch ready to be taken out(c) Measurement of un-extracted freed starch (starch loss in sago pith waste/ hampas) Sago pith waste waste/residue is called hampas (Cecil, 1992; Cecil et al., 1988; Manan et al., 2001). In order to investigate the amount of freed starch left in hampas which was not extracted during the extraction process (starch losses in hampas), 200 g samples of hampas in each process was taken and then further processed. The hampas then was re-processed further to extract starch which supposed not washed out in the former process. The starch is washed out from the hampas manually using water. The starch was separated from fibrous and cellular residue using a fine sieve (fine cloth). In this process, hampas was kneaded with water and the resulting slurry was then filtered using the fine cloth sieve and squeezed manually to obtain starch. The starch slurry passes trough the fine cloth sieve, and is then collected in a plastic bucket (Figure 5.15). This process is repeated several times until virtually no starch comes out from hampas. The hampas containing no starch is then discarded. Meanwhile, the starch is allowed to settle to

104 86 the bottom of the bucket for 2 hours, and subsequently the supernatant water is drained off. The wet starch in the bucket is taken out and weighed. The amount of starch losses in hampas was determined using equation (5.4): w Sh h 100 % (5.4) w H (a) Kneading (b) squeezing Figure 5.15 Manually sago starch extraction to re-extract the starch left in hampas 5.2 Results and discussions The performance of sago starch extractor developed was tested based on experimental conditions. The function of this extractor is to separate as much freed starch as possible from the repos. Separation is done in two stages of screening, e.g. (a) a coarse screening operation which is placed in the extraction cylinder (as shown in Figure 5.8) removes/retain most of the hampas and (b) fine screening operation, using fine cloth which is placed on a open wooden box (point No.10 as shown Figure 5.7) to separate the starch from fine hampas. Soluble components that are also exist in the sago pith such as sugars, proteins and many of the other constituents are dissolved and pass through the screens along with starch (Cecil, 1992; Cecil et al., 1988; Manan et al., 2001). These soluble materials caused the color of starch suspension become brownish instead of white.

105 Extraction efficiency The efficiency of starch extraction depends on how carefully the operation is managed. The amount of starch obtained depends on the fineness of the rasping and the efficiency of washing the starch out of the rasped pith. The more finely the pith is rasped, the more starch can be extracted in the subsequent rinsing process. However, this makes it more difficult to separate the starch from the hampas (Cecil, 1992; Colon and Annokke, 1984). The relationship between stirrer blades rotating speed and extraction efficiency at four different numbers of stationary blades is shown in Figure Extraction efficiency (kg of repos/hour) no blade 4 blades 8 blades 12 blades Stirrer rotary blades rotating speed (rpm) Figure 5.16 Relationship between stirrer blades rotating speed and extraction efficiency Figure 5.16 shows that increases of stirrer blades rotating speed caused an increase of extraction efficiency. The higher the rotating speed the higher the extraction efficiency. It is also shown that the greater the number of stationary blades the higher the extraction efficiency. These imply that the extraction process is more effective at higher rotating speed than lower one. Moreover, the greater the number of stationary blades the more

106 88 effective the extraction process is. The highest extraction efficiency (491 kg /hour) was obtained at the condition of 12 blades, 200 rpm and the lowest one (257 kg /hour) was at the condition of no blades, 100 rpm. These results are consistent with those of Darma et al., (2010). Principally, the working mechanism of this extractor is very similar with traditional method which is both involving kneading and screening. In traditional method, kneading is done either by hand or foot (trampling). On the other hand, this extractor uses stirrer rotary blades instead of hand to knead the repos. During the stirring process, freed starch as well as others substances that present in repos were suspended into water. The suspended starch is then forced to pass through the screen. After passed through the screen, the starch suspension flowed to the sedimentation tank. To improve the starch separation process, the inner surface of screener is equipped with stationary blades. These stationary blades create turbulent flows/eddy currents of repos slurry (Figure 5.17) by which more effective releases starch granules compared with the steady state flow. In addition, at the condition of no stationary blades, not only the flow of starch slurry is almost steady state, it is also being created an empty space in the centre part of cylinder (Figure 5.18). This empty space reduces the cylinder s capacity, so less repos that can be inputted in. Basically, increase of stirrer blades rotating speed as well as number of stationary blades results in the high intensity of turbulence, consequently it increases the starch separation effectiveness. This results in an increase of the extraction efficiency. It should be noticed that during the extraction operation, sufficient water is needed to practically wash/release most of the freed starch out of the pulped pith. If too little water is used, freed starch will be left in the pulp and will be lost, but if too much water is used it will be more expensive to recover the starch from it (Cecil, 1992). Another important factor that has to be controlled carefully is that the amount of water supplied into the

107 89 cylinder extractor and the water (starch slurry) flowing out should be balanced. If the amount of added water is less than water that is flows out, the slurry in the cylinder extractor will be quite dense and become difficult to stir. In the extreme condition it could overload the engine or even caused serious damage to the extractor s components. On the other hand, if supplied water is more than that is allowed to flow out, it will spill out from the upper side of cylinder extractor. (a) (b) Figure 5.17 the flowing pattern of repos slurry in the cylinder extractor: (a) turbulent flowing of water (b) high intensity of turbulent flowing of repos slurry. (a) (b) Figure 5.18 Empty space in the centre of cylinder (a) and steady state flowing of repos slurry (b).

108 90 A mechanical sago extractor that has been developed in Serawak, Malaysia consists of an open wooden frame supporting mosquito netting in the form of a horizontal openended cylinder about 30 cm in diameter and 3 m long. A solid wooden shaft, with deep longitudinal ribs rotates at about 100 rpm about a horizontal axis inside the mesh cylinder. Wash water is distributed along the top of the screen, and passes through the screen into the repos being agitated inside the washer (Cecil at al., 1982). Moreover, Cecil (1992) reported that in rather larger factories, rotating screens are almost always used. Six rectangular frames holding the screen are joined together along their long side to form an open ended cylinder with a hexagonal cross-section. The frame is mounted on rollers which allow it to move. The assembly is mounted at a slight slope (about 5 %) so the repos which is introduced at higher end gradually moves down to the lower outlet end. The screen rotates around its long axis at 15 to 20 rpm. The water is sprayed onto the repos from a pipe inside the cylinder. Water is also sprayed onto and through the mesh at the top of cylinder to keep the screen clean. The starch and fine pulp is washed through the screen. Rajyalakshmi (2004) and Rakha et al. (2008) reported that in large scale processing of sago starch, a series of centrifugal sieves are used to remove coarse fibers, and cyclone separator are used to extract the starch which is then dried using a rotary vacuum drier followed by hot air drying. The Indonesia Technological Research and Applications Agency, ITRAA (1990) has also developed similar sago starch extractor which consists of a stirrer tube and horizontal open-ended rotating cylinder screen about 60 cm in diameter and 600 cm in length (Figure 5.3). The cylinder screen is mounted on rollers and driven by electric motor of 2.2kW. The assembly is mounted at a slope of 15 degrees. The rasped pith is fed at the higher end and gradually moves down to the lower outlet end during the screen rotate. Water is sprayed continuously onto the rasped pith (repos) from a pipe inside the cylinder. The starch slurry

109 91 and fine pulp is washed through the screen. Before the repos are fed into rotating screen, it is first stirred in a stirrer tube. The stirrer is made of stainless steel and rotates around its vertical axis at 1500 rpm. Similarly, The Indonesia Agency for Agricultural Research and Development, IAARD (2001) has developed an integrated sago starch processing machine. This machine consists of three main components i.e. rasper, extractor and sediment tank unit (Figure 5.4). The extractor unit is similar to those of ITRAA (1990) but smaller in size. Compared to the sago extractor that had been developed in Serawak as reported by Cecil et al. (1982), and Cecil (1992), and the sago extractor developed by ITRAA (1992) and IAARD (2001), the extractor developed in this study was simpler, easier to move from one location to another (portable) and cheaper. The stirring and screening processes are carried out simultaneously in the same unit. Therefore, overall the extractor s construction is simpler and smaller in size. The former are suitable for medium and large scale extraction of sago starch, while the latter is more suitable for small scale one. Furthermore, this extractor is very easy to operate and can be owned by single farmer or a group of farmers Starch percentage and starch yield Figure 5.19 shows the relationship between stirrer blades rotating speed and starch percentage at four different numbers of stationary blades, and the relationship between stirrer blades rotating speed and starch yield is shown in Figure As shown in Figure 5.18 that for the three different number of stationary blade (no blade, 4 blades, and 8 blades) starch percentage slightly increased with the increase of stirrer blades rotating speed. The higher the rotating speeds of stirrer blades the higher the starch percentage resulted. Meanwhile, for the condition of 12 blades, increases rotating

110 92 speed of stirrer blades results in almost the same starch percentage for the three rotating speed. 25 Starch percentage (%) No blade 4 blades 8 blades 12 blades Stirrer rotary blades rotating speed (rpm) Figure 5.19 Relationship between stirrer blades rotating speed and starch percentage Wet starch yield (kg/hour) No blade 4 blades 8 blade 12 blades Stirrer rotary blades rotating speed (rpm) Figure 5.20 Relationship between stirrer blades rotating speed and starch yield. In general, an increased rotating speed of stirrer blades as well as an increased number of stationary blades results in a higher starch percentage. Therefore, the highest starch percentage (20.54 %) resulted from the condition of 12 blades, 200 rpm while the lowest one (15.9 %) was at the condition of no blade, 100 rpm. Based on the starch that

111 93 left in hampas which varied from 0 % to 2 %, this indicates that more than 98 percent of freed/loosen starch was recovered. These results support the previous study (Darma et al., 2010) who tested the similar type of sago extractor. Kamal et al., (2007) had used two new techniques (laboratory-scale) to extract starch from sago pith and found that the starch percentage were respectively 13 % and 26 %. In the first technique, equipment was blender which was used to extract starch from raw sago by grinding; aided by sufficient amount of water. Resulting starch slurry was filtered and squeezed manually to produce starch paste. The second technique involved equipment which extracted sago starch by dry grating followed by squeezing. Less water was used. These authors concluded that the ideal processing system of efficient sago starch production might be an integration of both blending and mechanized squeezing into one unit operation, aided by controlled amount of water. However, the use of blender was not practical to be applied for both small scale and large scale of sago starch production. Starch yield depends on both extraction efficiency and starch percentage. Figure 5.20 shows that the higher the stirrer blades rotating speed the higher the starch yield. Also the greater number of stationary blades the higher the starch yield resulted. These results indicate that the higher rotating speed of stirrer blades as well as greater number of stationary blades the more effective the extraction process. As a result, higher starch yield was resulted at the condition of higher rotating speed of stirrer blades as well as greater numbers of stationary blades. The highest starch yield (101 kg/hour) resulted in the condition of 12 blades; 200 rpm while the lowest one (41 kg/hour) was at no blade, 100 rpm. The highest starch yield that resulted in this study was higher compared to the previous study (Darma et al., 2010) and Istalaksana et al. (2011) which resulted in starch yields of 33 kg/hour and 79 kg/hour respectively. This higher starch yield is due to the higher efficiency of starch extraction as a result of using a better screener system (not only

112 94 at the bottom of the cylinder but also in the whole circumference of inner cylinder extractor). According to Cecil (1992) starch yield depends greatly on the sophistication of the method employed. Recently, there have been extensive studies on starch extraction and many are focusing on improving and increasing the efficiency, and subsequently the starch yield (Kamal 2007) Starch Left in Sago Pith Waste (starch loss in hampas) The relationship between stirrer blades rotating speed and starch left in hampas at four different numbers of stationary blades is shown in Figure The more the starch left in sago pith waste indicates that the extraction process is less effective and vise versa. It should be mentioned here that in this study only the freed starch left in hampas was measured. Therefore, it does not mean that there is no starch at all left in hampas. Unfreed starch remains either trapped within the parenchyma cells or the sago fibres. This was due to not the entire cell walls were ruptured in the preceding process (rasping process). In the extraction process only freed starch can be extracted while the un-freed starch still remains in hampas. 2.5 Starch loss in hampas (%) No blade 4 blades 8 blades 12 blades Stirrer rotary blades rotating speed (rpm) Figure 5.21 Relationship between stirrer blades rotating speed and starch loss in hampas.

113 95 As shown in Figure 5.21, for the three different numbers of stationary blades (no blades, 4 blades, and 8 blades), the starch left in hampas decrease with the increases of stirrer blades rotating speed. Meanwhile, for the condition of 12 blades, increases rotating speed of stirrer blades results the same amount of starch left in hampas i.e. 0 %. This was implies that at the condition of 12 blades, practically 100 % of the freed starch was extracted in the extraction process. Therefore, no starch at all remains in hampas. In general, increased rotating speed of stirrer blade as well as increased number of stationary blades results a lower starch left in hampas. The highest amount of starch left in hampas (2 %) resulted from the condition of no blades, 100 rpm. This indicates that the greater the number of stationary blades, the more effective the extraction process was and vice versa. These results were consistent with those of Darma et al., (2010). The amount of starch loss in hampas that resulted in this study was lower than those of IAARD (2001), which resulted in a starch loss in hampas of 2.4 % %. In similar study, Cecil at al., (1982) and Cecil (1992) reported that the amount of starch losses in hampas at several sago starch factories in Serawak, Malaysia varied from 19.5 % to 29.4 %. This difference may be due to the different techniques that have been used to disintegrate the pith (different characteristics of sago pith rasper). Manan et al., (2001) reported that the amount of starch disposed as sago residue in East Malaysia alone accounts for nearly 50 % of the total Malaysian imports of starch per year, which totals approximately 40,000 tons. It is well known that the efficiency of starch extraction depends largely on the degree and mode in which cell walls were ruptured. The more finely the pith is rasped, the more starch can be extracted in the subsequence rinsing process but more difficult to separate the starch from the hampas (Cecil, 1992; Colon and Annokke, 1984).

114 96 Figure 5.22 Sago pith waste called hampas. 5.2 Conclusions In this study, sago starch extractor with stirrer rotary blades was developed and the performance of the extractor was tested. Overall, all parts of the developed sago starch extractor work and function properly and has higher performance compared to previous ones. In the extraction experiment, three levels of stirrer blade rotating speed (i.e. 100 rpm, 150 rpm, and 200 rpm), and four levels of stationary blade number (i.e. no blade, 4 blades, 8 blades, and 12 blades) were tested. From this experiment the following can be concluded: (1) Extraction efficiency increased with the increase of both stirrer rotary blades rotating speed and the number of stationary blades. The higher the stirrer blades rotating speed the higher the extraction efficiency. Likewise, the greater the number of stationary blades the higher the extraction efficiency was. The highest extraction efficiency (491 kg /hour) was found at the condition of 12 blades, 200 rpm, while the lowest one (257 kg of repos/hour) was at no blade, 100 rpm. (2) Starch percentage and starch yield increased with the increase of both stirrer rotary blade and number of stationary blades. The higher the stirrer blades rotating speed the higher the starch percentage and starch yield. Similarly, the greater the number of

115 97 stationary blade the higher the starch percentage and starch yield. The highest starch percentage (20.54 %) and the highest starch yield (101 kg/hour) were resulted in the condition of 12 blades, 200 rpm. (3) The amount of freed starch left in pith waste (starch loss in hampas) decreased with the increase of stirrer rotary blades rotating speed as well as increase of number of stationary blades. The higher the stirrer blades rotating speed the lower the starch left in hampas. At the condition of 12 blades, 200 rpm practically no freed starch at all (0 %) was left in hampas. (4) Based on the results obtained in this study and using the equipment designed for this study, the best condition of extracting sago starch was 12 blades, 200 rpm in which resulted highest extraction efficiency, starch percentage, starch yield, and resulted the lowest starch left in hampas.

116 98 CHAPTER 6. VARIANT-2 OF IMPROVED STIRRER ROTARY BLADE TYPE SAGO STARCH EXTRACTOR In previous study (as discussed in chapter 5) showed that overall, the developed sago starch extractor worked and functioned properly. It has higher performance compared to those of Darma at al., (2010). However, it still has drawbacks that need to be overcome. The main constraint found in previous study was considerable amount of pith waste (fine hampas) passed through the screen along with water. This was due to the apertures of screener have been used (1.5 mm in diameter) are too large to retain the fine/tiny hampas. This fine hampas must be discarded and it was not allowed to flow into sedimentation tank because it will affect the purity of starch. For this purpose, the second screen which is made of fine cloth was necessary (Figure 6.1). In addition, the dimension of the second screener was too small, thus it is full with fine hampas quickly. Therefore, it is needed extra time and extra work to remove the fine hampas and in turn reduce the efficiency of extraction process. Figure 6.1 Second stage of screener was made fine cloth with wooden frame. The fine hampas has to be removed regularly as the screener was full.

117 99 Based on the constraints associated with previous study as mentioned above, in order to minimize the fine hampas that passed through the first screen, it is necessary to replace the screener with the smaller holes. In general, this experiment was similar to previous experiment (chapter 5), except for the screener have been used. Furthermore, the diameter of extraction cylinder was larger but shorter in height. This was aimed to increase the cylinder capacity as well as to make it easier to feed the repos into the extraction cylinder. The dimension of second stage screen was made larger so that it will not full in one process of extraction. By doing so, it was easier to handle the fine hampas, thus less time was needed to discard them. Previous research has shown that extraction performance was influenced by both stirrer blades rotating speed and the number of stationary blades. However, it is necessary to be investigated further the effect of stirrer rotating speed as well as number of stationary blades on extraction performance when using screener with smaller holes. It may be expected that smaller holes of screener will give higher performance. 6.1 Experiment materials and methods Overall structure and operating principles In general, the structure and feature as well as the operating principles are similar to the previous study (chapter 5). However, there were some differences such as screener s holes, size of the extraction cylinder and the dimension of second screener. Moreover, because the diameter of cylinder was larger but shorter, the entire dimension of the extractor was also different. Like previous study (chapter 5), this sago starch extractor consists of seven main components which are integrated in a single operational system (Figure 6.1). They were:

118 100 (1) Extraction cylinder, made of 2 mm thick steel. The cylinder s size was 103 cm in diameter and 100 cm in height (volume = 0,785 m 3 ). The lower end of the cylinder was a conical shape to prevent starch sedimentation incidence in the bottom of cylinder; (2) A screen, made of perforated stainless steel sheet with the holes size of 0.7 mm in diameter. The screen s diameter is slightly smaller (92 cm in diameter) than extraction cylinder and it is placed inside the extraction cylinder; (3) Stationary blades are made of 5 mm thick L- shape 50 mm x 50 mm steel bar. They are mounted vertically on the inner surface of screen; (4) Stirrer rotary blades, its function are to free starch granule from fiber and suspended into water; (5) Power transmission system, consists of v-belt, pulley and reduction gear box (WPX 80, ratio 10:1); (6) Power source, using a 6.5 HP gasoline engine; (7) Frame was made of 5 cm 0.5 cm equal angle steel bar. In addition, it is equipped with a pipe (2 inch in diameter) to flow starch suspension from extraction cylinder to the sedimentation tank. At the end of the pipe, it is equipped with a stop tap (valve) to control starch suspension flowing. In addition, because some fine fibre were also passed through the screen along with starch and water, so it necessary to be screened further to remove the fine fibre. For this purpose, a second stage screen which is made of 100 mesh stainless steel strainers was used and it was placed at the end of flowing pipe (Figure 6.2). Its size was much larger than those of previous one. Starch suspension from the extraction cylinder was passed through this second screen before it flows into the sedimentation tank. The fine hampas retained on the second stage screener was discarded manually.

119 101 Figure 6.2 Overall structure of Variant-2 stirrer rotary blades sago starch extractor (Note: main components are same as those of in chapter 5) Experimental conditions Like previous study (chapter 5), the functional parts of this extractor are screener (Figure 6.2) and the stirrer rotary blades. Previous study (chapter 5) has shown that as stirrer blades rotation speed increases, extraction performance was higher. Likewise, the greater the number of stationary blades result the higher extraction performance. This present study aimed to examine further the effect of stirrer blade rotating speed and number of stationary blade when smaller apertures of screener are used. The extraction performance was tested under experimental conditions are same as previously (chapter 5), i.e. three levels of stirrer blades rotating speed (100 rpm, 150 rpm and 200 rpm) and four levels of stationary blades numbers ( no blades, 4 blades, 8 blades and 12 blades). The screener holes (apertures) were 0.7 mm in diameter and it made of 1 mm thick stainless steel flat. Meanwhile the second stage screener also made of stainless steel with aperture 100 mesh. It is assembled at the bottom of rectangular wooden box (Figure 6.4). The size of wooden frame was 1 m x 2.5 m x 0.2 m.

120 102 (a) (b) Figure 6.3 Screener was ready to be assembled (a) and second stage screener (b) (a) (b) Figure 6.4 Screener with stationary blades in which extractor ready to be operated (a) and extraction process is occurring (b) Extraction efficiency measurement The process flow of the extraction operation that has been conducted in this study was same as previous one (as shown in Figure 5.9 in chapter 5). Similarly, the formula for extraction efficiency measurement was same as previous study (equation 5.1). sago rasper which was used in this study was cylinder type with sharp teeth (Darma et al., 2013) Starch percentage and starch yield measurement

121 103 The starch percentage and starch yield measurement as well as the procedure were same as chapter 5. Starch percentage and starch yield were defined using equation 5.2 and equation 5.3 respectively Measurement of un-extracted freed starch (starch loss in sago pith waste/ hampas) The procedure to measure the un-extracted starch (starch left in hampas) was same as chapter 5. The amount of starch left in hampas was determined using equation Results and discussions Extraction efficiency Figure 6.5 shows the relationship between stirrer blades rotating speed and extraction efficiency at four different numbers of stationary blades is shown in Figure Extraction efficiency (kg/hour) No blade 4 blades 8 blades 12 blades Stirrer blades rotating speed (rpm) Figure 6.5 Relationship between stirrer blades rotating speed and extraction efficiency As shown in Figure 6.5 that increases of stirrer blades rotating speed resulted an increase of extraction efficiency. The higher the rotating speed the higher the extraction

122 104 efficiency. Similarly, it is also shown that the greater the number of stationary blades the higher the extraction efficiency. This was related to the intensity of turbulent flowing of pulp (mixture of water and repos) in the extraction cylinder during the process (Figure 6.6). The higher the intensity of turbulent flowing the more effective the starch separation was. These trends were consistent with previous study (chapter 5). The highest extraction efficiency (1007 kg /hour) was resulted at the condition of 12 blades, 200 rpm and the lowest one (566 kg /hour) was at the condition of 4 blades, 100 rpm which was very closed to the extraction efficiency resulted from the condition of no blade, 100 rpm (578 kg/hour). Compared to the previous study (chapter 5), the extraction efficiency resulted in this study was twice higher. It was implies that extraction process occurred more effective compared to the previous one. This was because not only the extraction cylinder s capacity (100 kg of repos in each process) was larger but also less time was needed. Unlike previous study (chapter 5) where periodically the flowing of starch suspension was stopped as the second stage screener full with fine hampas, this was not happen in this study. During extraction process, starch suspension was flowed continuously from the extraction cylinder because the second stage screener never overcapacity (never full). The smaller holes of screener have been used retain more hampas. Therefore, less of them flow to the second stage screener and as a result less time was needed to discard them. Extraction time was twice shorter than previous one (chapter 5). Although second stage screener was big enough to retain fine hampas (never full in each process), the amount of starch suspension flow from extraction cylinder must be controlled carefully. The amount of water supplied into the extraction cylinder must be balanced with the amount of water flow out along with starch and fine hampas through flowing pipe.

123 105 (a) (b) Figure 5.6 the flowing pattern of repos slurry in the cylinder extractor: (a) almost steady state flowing (experimental condition of no stationary blade, 100 rpm) (b) turbulent flowing of repos slurry (experimental condition of 8 stationary blades, 100 rpm) (a) (b) Figure 5.7 (a) turbulent flowing of repos slurry (experimental condition of 12 stationary blades, 100 rpm, (b) turbulent flowing of repos slurry (experimental condition of 4 stationary blades, 200 rpm) Starch percentage and starch yield Figure 5.8 shows the relationship between stirrer blades rotating speed and starch percentage at four different numbers of stationary blades, and the relationship between stirrer blades rotating speed and starch yield is shown in Figure 5.9.