Pasting Properties Of Thermally Modified Sago Starch Ira Mulyawanti, Sari Intan Kailaku, Andi Nur Alam Syah, and Enrico Sjaifullah Indonesian Center for Agricultural Postharvest Research and Development Jl. Tentara Pelajar 12, Bogor 16114, Indonesia Email: iramulyawanti@yahoo.com Keywords: sago starch, heat moisture treatment, modified sago starch Abstract Sago is a potential commodity to be developed into an alternative carbohydrate source. To obtain a certain product from sago, a modification can be conducted to its starch characteristics. Heat Moisture Treatment (HMT) is a starch modification procedure that applies heat continuously in certain length of time with limited moisture content. The objective of this research is to observe the pastng properties of sago starch modification with HMT. Sago starch used was gained from Kabupaten Pandeglang, Banten. HMT condition was performed at temperature of 110⁰C and 28% moisture with duration time of 4, 8, and 16 hours to washed and unwashed natural sago starch. Result showed that unwashed and washed sago starch changed pasting properties with HMT condition (110⁰C, 28% moisture), and these changes also occur in line with the increase of HMT duration time. INTRODUCTION Starch was polysaccharide synthesized by green plants. Starch has unsoluble crystal form in water at ambiyen temperature and has a shape and size depending on the type of crops. In the developing of product diversivication based on charbohydrate, its starch characteristics was being a problem for the process of the products. Therefore the starch modification is important to do. A specific characteristic of starch affected by macromolecul ratio and granule structures. Starch granule consists crystalline and amorf structure in which the structure is formed by branched chain amylopectin interspersed by amorphous layers (Liu, 2005). Modified starch is done to address the shortage of native starch and increase its usefullness in industry. Modified starch is also expected has related characteristics for final product processing, such as, gel stability and strength, digestibility, solubility, etc. Some starch modification techniques that can be used include the Heat Moisture Treatment (HMT), annaeling, and cross linking. Beside that, starch modification is also did with enzymatic and genetic or biothechnology (Kaur et al. 2012). Heat Moisture Treatment (HMT) is an important physical treatment method utilized to improve the poor functional properties of native starch and is particularly favourable for food aplication (Sun et al. 2014). This technique is considered to be natura and safe when compared to chemical modification (Watcharatewinkul et al. 2014). HMT is physically starch modification techniques involving low evel of humidity (10-30%), with hight temperature heating (90-120⁰C) for 15 minutes-16 hours (Zavareze E. R., and A. R. G. Diaz. 2011). HMT has been shown to change starch properties by facilitating starch chain interactions within the amorphous and crystalline domains and or by disrupting starch crystallites, the extent of these changes being influenced by starch composition, organization of amylose and amyopectin within the native granules, and by the conditions (temperature, moisture, time) prevailing during HMT(Varatharajan et al., 2011). Structural changes within 469
granules resulting from HMT induce changes to granular swelling behavior, crystallinity, amylase leaching, thermal transition properties, thermal stability,and pasting behavior (Varatharajan et al., 2011; Kim and Huber, 2013). Sago is a potential commodity to be developed into an alternative carbohydrate source. Starch from sago is the only example of an industrial starch derived from the trunk of the sago palm (Metroxylon sagu Rottb.). Although some of the physicochemical properties of sago starch are quite similar to those of common starches (potato, tapioca), it also has unique characteristics (Abdorreza et al. 2012). This paper aims to examine changes in the characteristics of modified sago starch Heat Moisture Treatment (HMT). METHODOLOGY The sago starch used in this research was obtained from Pandeglang, Banten, while the equipments were analytical scale, oven, refrigerator and other analytical equipments. Sago starch treatment with HMT was conducted at temperature of 110 0 C with moisture content of 28% for 4, 8, and 16 hours. HMT was done to washed and unwashed sago starch. (Figure 1). Observation was performed on chemical characteristics of the raw material (sago starch) and pasting properties of HMT modified sago starch using Brabender Viscograph. RESULTS AND DISCUSSION Chemical Characteristics of Sago Starch The main content of sago starch is carbohydrate. Analysis result showed that sago starch used in the experiment contained 88,5% carbohydrate that consisted of starch, sugar or crude fiber remained from the extraction process of starch. The extraction process of sago starch was done by adding water to the grated middle part of the sago tree trunk prior to repeated extortion and precipitation. Water was then separated and the sago starch was dehydrated. The effectivity of drying process affected the moisture content of sago starch obtained. The analysis results showed that the moisture content of the sago starch was 20%. Compared to Indonesian National Standard (SNI) the moisture content of sago starch used in the experiment was considerably high. This was influenced by the drying process which was still done by traditionally sundrying. This process is highly dependent on the intensity of the sunlight and the ongoing season. Ash and protein content respectively was 0,27% and 0,12%. The lower ash and protein content showed the better purity of the sago. SNI 1995 requires maximum ash and protein content of 0,5% and 0,3%. Chemical characteristics of sago starch is presented in Table 1. Pasting Properties of Modified Sago Starch Results showed that unwashed and washed sago starch increased peak, hot paste, breakdown, and set back value. According to Collado and Corke (1999), ph and time of HMT influenced the pasting properties of modified sweet potato starch. On sago starch, ph alteration during washing affected the pasting properties with higher increase of peak following the longer HMT duration. On the contrary, modified unwashed sago starch showed lower increase of peak. High ph value causes changes in the interaction of hydrogen between amylose and amylopectin molecules, and this causes more expansion during gelatinization. Unwashed modified sago starch decreased in peak, hot paste, and set back value compared in line with the length of time of HMT. The decreases may due to 470
the degradation of starch granules and the accompanying decrease of the degree of cross linking among moleculars (Sun et al. 2013). The pasting properties of native and modified sago starch were presented in Table 2. HMT duration of 8 and 16 hours resulted no different breakdown value between washed and unwashed starch, that was 150 BU and 170 BU, while 4 hours HMT resulted a higher breakdown value for unwashed starch compared with washed starch. This concluded that HMT for 4 hours preceded by washing process can increase the stability of paste during heating and stirring. However, HMT for 8 hours showed the best paste stability for both washed and unwashed starch, proven by the lower breakdown compared with the other treatments. Cold paste of unwashed and washed starch increased with HMT compare with native starch. The cold paste of unwhased starch decreased in line with the length of HMT duration time. In the other side, cold paste of washed starch increased at HMT duration time of 8 hours and decreased at HMT diuration time of 16 hours. Higher cold paste indicates that the better of ability of the starch to form a gel. CONCLUSION Unwashed and washed sago starch changed pasting properties with HMT condition (110⁰C, 28% moisture), and these changes also occur in line with the increase of HMT duration time. Literature Cited Abdorreza MN, M. Robal, L.H. Cheng, A.Y. Tajul, A.A. Karim. 2012. Physicochemical, thermal, and rheological properties of acid-hydrolyzed sago (Metroxylon sagu) starch. Food Science and Technology 46: 135-141. Adebowale KO, Olu-owolabi BI, Olayinka OO, Lawal OS. 2005. Effect of heat moisture treatment and annealing on physicochemical properties of red sorghum starch Afr. J. Biotechnol, 4 : 928-933 Ahmad BF, Williams PA, Doublier J, Durand S, Buleon A. 1999. Physicochemical characterization of sago starch. Carbohydr Polym, 38: 361-370. Collado LS and Corke H. 1999. Heat-moisture treatment of sweet potato starch. Food Chem. 65 : 339-346. Gunaratne A., Hoover R. 2002. Effect of heat-moisture treatment on the structure and physicochemical properties of tuber and root starches. Carbohydr. Polym. 49: 425 437. Kaur F., F. Ariffin, R. Bhat, A. A. Karim. 2012. Progress in starch modification in the last decade. Food Hydrocolloid 26:398-404. Kim Jong-Ye and K C Huber. 2013. Heat moisture treatment under mildly acidic conditions alters potato starch physicochemical properties and digestibility. Carbohydrate Polymers 98 :1245 1255. Liu, Q. 2005. Starch modifications and applications. In S. W. Cui (Ed.), Food carbohydrates: Chemistry, physical properties, and applications : 357 406. CRC Press,cap. 8 Nazan, K.T. and Sßahbaz, F. Water vapor permeability, tensile properties and solubility of methylcellulose-based edible films. 2004. Journal of Food Engineering 61: 459 466. Purwani, E.Y. Widaningrum, R. Thahir, dan Muslich. 2006. Effect of Moisture Treatment of Sago Starch on Its Noodles Quality. Indonesian Journal of Agricultural Science 7 (1):8-14. 471
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Tables Table 1. Chemical characteristics of sago starch. Component Content (%) Content (%)(SNI) Moisture content 20 Max 13* Ash content 0,27 Max 0,5* Protein content 0,12 Max 0,3* Fat content 0,17 - Carbohydrate content 88,5 - *Source : SNI 01-3729-1995 Table 2. Pasting properties of modified sago starch with HMT at 110 C. Treatments Initial gelatinization temp ( o C) Peak temp ( o C) Peak Hot paste Breakdown Cold paste Set Back Value Native sago 75 82,5 400 230 170 430 200 4h 75 81 530 340 190 640 300 Unwashed 8h 75 79,5 430 280 150 520 240 16h 75 79,5 420 250 170 430 180 Washed 4h 75 79,5 520 360 160 690 330 8h 75 79,5 560 410 150 770 360 16h 75 79,5 570 400 170 690 290 473
Figures Sago Starch Moisture content adjustment (28%) Storage in refrigerator (5 C, 24 h) Oven drying (110 C, 4, 8, and 16 h) Modified sago starch Figure 1. Flowchart of HMT process of sago starch (Purwani et al., 2006) (a) (b) (c) (d) (e) (f) Figure 2. HMT modified sago starch; unwashed and 4h HMT (a), unwashed and 8h HMT (b); unwashed and 16h HMT (c); washed and 16h HMT (d); washed and 8h HMT (e); washed and 4h HMT (f). 474