SCREENING OF POTATO VARIETIES FOR CHEMICAL COMPOSITION AND PROCESSING

Transcription

1 SCREENING OF POTATO VARIETIES FOR CHEMICAL COMPOSITION AND PROCESSING Thesis submitted to the University of Agricultural Sciences, Dharwad in partial fulfillment of the requirements for the Degree of MASTER OF HOME SCIENCE IN FOOD SCIENCE AND NUTRITION BY HABUNG GANGA DEPARTMENT OF FOOD SCIENCE AND NUTRITION COLLEGE OF RURAL HOME SCIENCE, DHARWAD UNIVERSITY OF AGRICULTURAL SCIENCES, DHARWAD JUNE, 2011

2 ADVISORY COMMITTEE DHARWAD JUNE, 2011 (UMA N. KULAKARNI) MAJOR ADVISOR Approved by : Chairman : (UMA N. KULKARNI) Members : 1. (NIRMALA N. YENEGI) 2. (BASAVARAJ N.) 3. (K. RAMACHANDRA NAIK) 4. (NAGARATNA UPPINAL)

3 C O N T E N T S Sl. No CERTIFICATE ACKNOWLEDGEMENT LIST OF TABLES LIST OF FIGURES LIST OF PLATES LIST OF APPENDICES 1 INTRODUCTION REVIEW OF LITERATURE Chapter Particulars 2.1 Physico chemical characteristics of potato varieties 2.2 Processing and screening of potato varieties MATERIAL AND METHODS 3.1 Collection of potato tubers 3.2 Physico-chemical composition of potato tubers 3.3 Optimization of processing of potato products 3.4 Screening of potatoes for processed products 3.5 Organoleptic evaluation of processed products 3.6 Statistical analysis RESULTS 4.1 Physico-chemical composition of potato tubers 4.2 Optimization of processing of potato products 4.3 Screening of potatoes for processed products DISCUSSION 5.1 Physico-chemical composition of potato tubers 5.2 Optimization of processing of potato products 5.3 Screening and processing of potato tubers 6 SUMMARY AND CONCLUSIONS REFERENCES APPENDICES

4 LIST OF TABLES Table No. Title 1 Physical characteristics of potato varieties 2 Morphological characteristics of potato varieties 3 Total potato defects (TPOD) of potato varieties 4 Chemical composition (%) of potato varieties 5 Sugar content of potato varieties (mg/100g) 6 Correlation (r) between physical parameters and chemical composition (%) of fresh potatoes 7 Preliminary trials for optimization of chips preparation 8 Preliminary trials for optimization of pressure cooking of potatoes 9 Preliminary trials for optimization of microwave baking of potatoes 10 Quality parameters of raw potatoes from different varieties (g%) 11 Quality parameters of fried potato chips 12 Organoleptic profile of potato chips from different varieties 13 Acceptability indices of potato chips Quality parameters of pressure cooked potatoes from different varieties Sensory mean scores of pressure cooked potatoes from different varieties 16 Acceptability indices of pressure cooked potatoes 17 Quality parameters of potato varieties baked in microwave oven 18 Sensory mean scores of microwave oven baked potato varieties 19 Acceptability indices of baked potato varieties Correlation (r) between physical parameters and quality of processed products (%). Correlation (r) between chemical composition (%) of raw potatoes with quality of processed products (%) Correlation (r) between chemical composition (%) of raw potatoes with organoleptic parameters of potato chips Correlation (r) between chemical composition (%) of raw potatoes and sensory profile of respective pressure cooked potatoes Correlation (r) between chemical composition (%) of raw potatoes and sensory profile of respective microwave baked potatoes

5 LIST OF FIGURES Figure No. Title 1 Research design 2 Flow chart for chips preparation 3 Flow chart for cooking of potatoes

6 LIST OF PLATES Plate No. Title 1 Automatic slicing machine used for chips preparation 2 a.different potato varieities b.different potato varieties 3 a.chips from different potato varieties b.chips from different potato varieties 4 a.pressure cooked potatoes from different varieties b.presuure cooked potatoes from different varieties 5 a.microwave baked potatoes from different varieties b.mircrowave baked potatoes from different varieties

7 LIST OF APPENDICES Appendix No. Title I Score sheet for organoleptic evaluation of potato chips II Score sheet for organoleptic evaluation of pressure cooked potato III Score sheet for organoleptic evaluation of microwave baked potato

8 1. INTRODUCTION Potato (Solanum tuberosum L.) popularly known as The king of vegetables, is the fourth most important food crop in the world after rice, wheat and maize. It occupies the top most position among tuber crops followed by cassava, sweet potato and yams. Potato is an ideal crop grown very well in multiple cropping system prevalent countries having tropical and subtropical agro climatic conditions. Its diversity is vast with approximately 5000 varieties of potatoes are known and most cultivated varieties belong to the species (Solanum tuberosum L). Potato is a lubacious dicotyledon, regarded as a perennial because of its ability to reproduce vegetatively, although it is cultivated as a ground stem with varying size, shape and colour according to the cultivar. One of the important varietal characteristics is early maturity. The period of planting and sprouting until harvesting alters and depends greatly on the length of growing season, which can oscillate between 60 to 200 days. Potato is a major food crop, grown in more than 100 countries. The native South Americans brought potato under cultivation by 2000 years ago before the Spanish conquest. It was introduced in India by the Portuguese sailors during early 17th century and its cultivation was spread to North India by the British. At present China, Russia, India, Poland and U.S.A. contribute a major share of total world production. India holds the 3 rd position in production and 4 th in area under cultivation of potato in the world. It is grown in an area of 1.41 m ha with an average annual production of 24 MT (Raj et al., 2007). About 90 percent of the total potato production in India is contributed by the Indo-Gangetic plains. Potato is one of the main commercial crop grown in 23 states of India of which Uttar Pradesh, West Bengal, Bihar, Punjab and Gujarat account a lion s share of the total production. The annual compound growth rate of potato is higher than other major food crops in respect of area, production and productivity (Pandey et al., 2009). However, despite the large production in India, the actual availability of potato is much lower because, 10 percent of the total produce is used as seed and about percent is wasted during harvesting as well as post-harvesting handling due to non-availability of sufficient cold storage facilities and rest is utilized for culinary purposes (Raj et al., 2007). One of the important problems faced by developing countries in general and India in particular, is the ever increasing population. At the turn of century, the world population is expected to touch the eight billion mark while population of India would reach 1.2 billion by 2020 (Shekawat, 1999). According to projections from Government of India, the country will be required to produce an additional 5.6 million tonnes of food grains annually. Therefore, in order to increase agricultural production further, the only option is to grow high productivity crops, like potato. As quoted by Dr. M.S Swaminathan, the eminent agricultural scientist, The present vulnerability of national food budgets to the vagaries of weather arises from our dependence on too few crops for our daily bread. Potato can help to widen the food supply base and thereby help to minimise the risk of serious food shortages in the tropics and subtropics. Due to greater demand for food and higher pressure on the limited land available to produce required quantity of food and overall food and nutrition security of the country; India should identify and promote a crop which is not only highly productive but also nutritionally balanced. Potato ranks first in dry matter as well as edible protein production compared to the three major cereals viz., rice, wheat and maize. Besides, potato produces more nutrients per unit area and time than the major cereals. As observed by Dr. W.G. Burton, an eminent potato physiologist, it is a reasonable approximation to state that the nutritive value of the produce from a hectare of potatoes would have been about three times as great from one hectare of cereals (Shekawat, 1999). Hence, potato may prove to be a useful tool to achieve the nutritional security of the nation. Indian vegetable basket is incomplete without Potato, because the dry matter, edible energy and protein content of potato makes it nutritionally superior vegetable as well as staple food not only in the country but also throughout the world. Now, it has become as an essential part of breakfast, lunch and dinner worldwide. According to the latest FAOSTAT statistic, potatoes account for only about 2 per cent of the world s dietary energy supply. As a staple food, potatoes are globally less important than rice, wheat and maize, which account for 20 per cent, 18 per cent and 5 per cent respectively.

9 The composition of potato varies with the cultivar, growing area, and fertilization regime (Liu et al., 2007). Freshly harvested potato contains about 80 percent water and 20 percent dry matter. Starch accounts percent of the dry matter. These are non fattening, nutritious and wholesome food which supply important nutrients to the diets. Potato contains significant quantities of protein, vitamin C, carbohydrate, iron and to lesser extent vitamin B- complex and vitamin A. Proteins of potato posses a high biological value and its starch typically fall in Type-II resistant starch and has been successfully used as fat replacer (Sood et al., 2008). Potatoes also contain dietary antioxidants, which play a part in preventing diseases related to ageing. Presence of dietary fibre in potato, benefits the health. Since potatoes are consumed as a main vegetable in the developing countries, they form an important source of antioxidants (Marwaha et al., 2008). Potato is one of the most versatile foods which can be cooked in many ways. It is available all round and may be cooked by various means. Potato forms a unique food because it can fit into any meal (Ezekiel et al., 1999). The major processing technologies commonly used are: moist heat methods (boiling and curry), dry heat methods (roasting and baking) and frying (chips, battered cakes). In recent years, the glycemic index (GI) has been transformed from a potentially useful tool in planning diets for diabetic patients, to a promising strategy for the prevention of diabetes, dyslipidemia, cardiovascular diseases and even certain cancers in the general population. Decreasing sugar and/or digestible starch and lipid intake as well as increasing dietary fibre intake are widely accepted dietary strategies for the prevention of these diseases. When potatoes are cooked for consumption, starch is gelatinized and becomes susceptible to hydrolysis by α-amylase. However, linear starch molecules such as amylose in the gelatinized starch system are able to retrograde to form a single or double helical structure that is highly resistant to hydrolysis by α-amylase. Thus, it is very important to understand this characteristic of potato starch since it plays a key role in the digestibility of potato products and the glycemic response in human subjects (Liu et al., 2007). The demand for processed potato products is increasing continuously in the present day mainly due to improved living standards, urbanization growth, preference of new generation and expanding tourist trade. Potato can be processed into a number of products and the quality requirements of potato vary for different products and suitability of particular cultivars for specific products. Besides the shape and size of the tubers, dry matter, specific gravity and starch content of potatoes are the most important factors in determining their suitability for processing. In the unorganised sector dehydrated potato products are commonly prepared of which dehydrated potato chips is the most important dehydrated product (Das et al., 2001). In India boiling and frying are most popular processing methods employed during cooking of potato. Medium to large size tubers with shallow eyes are preferred for most of the processed products as these result in lower peeling losses. For preparation of chips, fries and dehydrated products,dry matter, specific gravity, reducing sugars and high starch content should be more than 20 percent, 1.080, 0.1% on fresh weight basis respectively (Pandey et al.,2009; Ramezani and Aminlari, 2004). Storage of potatoes at 2-4 C is ideal for long term utility but storage temperature of 8-10 C is ideal for preparation of chips. The quality of potato chips is affected by tuber variety, storage condition prior to processing, slice thickness, blanching time and temperature, nature of oil used, temperature and period of frying. Colour is one of the most important factors in the evaluation of potatoes for chipping. The optimum colour is golden brown. Processing industry is highly developed in USA, Canada and Europe. But in India, only after the release of Kufri Chipsona-1 and 2 in 1998 and Kufri Chipsona-3 in 2005, potato processing was revolutionised. Organized processing industry consumes less than 2 percent of the total potato produce in the country compared to percent in developed European countries and North America. Potato processing is increasing at very fast pace in India. Currently country processes about 6% of potato produced. Potato processing is expected to grow by 10% by the year 2015 as reported by Central Potato Research Institute, Shimla (Anon., 2009) Projections for 2020 suggest that the area under potato crop will rise to 2 million ha and production to reach approximately 50 million MT. Increased potato production has led to the realisation that processing is essential to sustain the increasing potato production in the country.

10 Indian snack industries use potatoes for producing products like potato chips, potato sticks, alu Bhujia, puffed potatoes, potato powder, potato flakes and French fried potatoes. Production of potato chips has been increasing steadily each year and hence potato industry is growing steadily. The potato chips business is increasing at a rate of 10-12% each year, consuming over 34% of the total processed volume of potato. People now feel the need of ready-to-eat foods which is not only attractive and appetizing but also rich in calories (Nema and Prasad, 2004). With the establishment of potato processing plant, there is an increasing demand for suitable raw material as different brands of potato chips including Lays (Pepsico India Pvt. Ltd), pogo chips (GP foods) and potato flakes (king brand) are being manufactured. The demand of potato flakes is growing continuously in India due to increased usage in fried snacks, extruded products, soup powders, pasta, fabricated chips and French fries etc. India presently imports about 3500 MT of potato flakes every year, although, there are four big flakes manufacturing industries in India (Marwaha et al., 2008). Potato being a vegetable with 80% of moisture in its fresh form is also subjected to price fluctuation and causes lot of economical loss to the farmers during glut seasons. Further increased cost of cold storage and appreciable loss in storage is making the growers to go for potato processing. Among the processed products, chips are the most popular ready-to-eat snacks in India. Potato consumption in different processed products need to be enhanced to sustain the increase in production and to ensure remunerative prices to the farmers. Processing of the bulky perishable potatoes into various processed products is a viable option which can help to extend the shelf life, solve the problem of storage, cater to consumer preferences belonging to different age groups and social strata, serve as a means to maximise the supply in off-seasons thereby maximizing potato utilization. With specifications for morphological and biochemical traits, screening of potato cultivars suitable for either direct consumption or processing is a prerequisite for processors, industrialists and consumers in the food chain. Employing the common and feasible methods of processing, the present study on screening of potato cultivars for chemical composition and processing was formulated with the following objectives, 1. To study the physical characteristics of different potato varieties 2. To estimate the chemical composition of different potato varieties 3. Optimization of processing of potato products 4. Screening of varieties for processing quality of potato

11 2. REVIEW OF LITERATURE Potato (Solanum tubersum L.), the most valuable tuber crop is produced in 150 countries. As a crop in developing world, it comes fourth in dollar value among major food crops. Potatoes currently have the highest rate of production growth in most developing countries and the main stay in the diet of people in many parts of the world. On an average, about 28% of total potato produced throughout the world is processed. The related literature pertaining to the study entitled Screening of potato varieties for chemical composition and processing has been reviewed under the following subtitles:- 2.1 Physico-chemical characteristics of potato varieties. 2.2 Processing and screening of potato varieties. 2.1 PHYSICO-CHEMICAL CHARACTERISTICS OF POTATO VARIETIES Physico-chemical characteristics of potatoes are influenced by many factors such as season, soil type, agronomic practices, species and varieties. Misra and Chand (1990) conducted an experiment to see the relationship between size of tuber and chemical composition of potato in Meerut. A negative linear relationship was observed between tuber size and total phenolic content (44.0mg/100g for 1.5cm and 4.8mg/100g for 8.0cm) as well as reducing sugar (150mg/100g for 1.5cm and 0.3mg/100g for 8.0cm).The tuber size did not affect dry matter, sucrose and ascorbic acid content of the two varieties. Thus bigger the tuber, better the processing characteristics so far as reducing sugars and phenolics content are concerned. Physical properties of different potato cultivars were studied by Tabatabaeefar (2002) in Iran. Among the four varieties studied, Draga and Agria had longer diameter and larger masses than other two varieties. Average specific gravity of the Vital variety (1.3) was higher than other varieties. All the varieties exhibited ellipsoidal shape. The per cent spherecity for Draga, Ajacks and vital varieties was 81per cent. With minimum per cent sphericity (71) and highest length to width ratio (1.5), Agria variety was less spherical. As the diameter of tuber increased, volume of potato increased linearly. Evaluation of potato cultivars for processing into crisps was carried out by Abong et al. (2010) in Kenya. Majority of the cultivars with exception of Roslin Tana, Desire, Roslin Ebura, Nyayo, Tigonilong and Kihora had acceptable physical characteristics suitable for processing. Tuber diameter varied significantly (p 0.05) among the cultivars ranging from 43 mm in Tigoni long to 56 mm in Kenya Sifa and Clone The specific gravity of the cultivars varied from to and dry matter contents from to per cent. Majority of the cultivars were round in shape. Reducing sugar levels varied significantly (p<0.05) among the cultivars and ranged between 0.07 per cent and 0.4 per cent. Changes in reducing sugars content and chip colour of tubers during storage at different temperatures was observed by Singh and Ezekiel (2008) in Jalandhar. Dry matter content varied with the cultivar and growing location. Processing cultivars Kufri Chipsona-1 and Kufri Chipsona-2 had higher dry matter content (24.4 and 25.8 % respectively) as compared to other cultivars. Least dry matter content was observed in Kufri Pukhraj (15.6 %). Reconditioning was effective in reducing the sugar content significantly (p 0.05), however was less effective in improving the chip colour. Yaghbani et al. (2006) investigated composition and characterization of starch extracted from various potato cultivars in Golestan province of Iran. The diameter of potato starch granule were shown to range from 34.2 to 42.1µm with a mean of , indicating that the granule size had no significant differences among potato varieties. The yield of potato starch varied from 9 to 12.6% on fresh weight basis. The highest and lowest yield of starch was observed in Concord and Draga respectively. The starch yield was directly correlated to the dry matter content of the tubers, which ranged between 17.2 and 22. Among the six potato cultivars, the average value of the amylase content was lowest in Sante (24.4%) and highest in Draga (27.1%).

12 Study on distribution of dry matter and sugars of potato cultivars namely: Kufri Chipsona-1, Kufri Chipsona-2, Kufri Jyoti, Kufri Lauvkar and Atlantic were undertaken by Kumar and Ezekiel (2004) in Himachal Pradesh. The highest values of dry matter were obtained in stem end cortical tissue of Kufri Chipsona-2 (27.5%) and lowest in pith region of Kufri Lauvkar (14.8%). The dry matter distribution pattern was more or less similar when compared within the individual varieties. The highest mean values for reducing sugar were obtained in stem and cortical tissue (260mg/100g). Sucrose content has also been found to vary significantly within the tuber. Physico-chemical properties of dry matter and starch from potatoes grown in Canada were estimated by Liu et al. (2007).Per cent total starch, dietary fibre, protein, free sugar and apparent amylose content of AC Stampede Russet, Russet Burbank and Karnico potato dry matter ranged between 70.5 to 72.4, 5.2 to 5.6, 7.1 to 9.7, 3.3 to 6 and 29.7 to 33.3 respectively. Comparison of the specific gravity of four different cultivars of potato in Iran indicated that Herta and Cosima had the highest values of specific gravity (1.088 and respectively) and Picaso had the lowest (1.068) specific gravity. The solid content of different cultivars differed significantly. The starch content of Picaso (55.3 g/100g) was significantly lower than other varieties. Picaso (2.4 g/100g) contained the highest level of reducing sugar and Agria cultivar content lowest 1.2 g/100g (Ramezani and Aminlari 2004). Sood et al. (2008) in Hissar conducted a biochemical evaluation of potato tubers and peels of Kufri Chipsona-1, Kufri Chipsona-2, Kufri Ashoka, Kufri Sutlej, Kufri Pukhraj and Kufri Jawahar. The energy value exhibited a range of 314 to 375 in tubers and 278 to 349 kcal per 100g in peels. Starch is the major constituent of potato tubers and it varied from (Kufri Sutlej) to (Kufri Chipsona-1) per cent and average to per cent. The highest amylose content was recorded in Kufri Chipsona-1(31.84%) and the lowest in Kufri Jawahar (19.28%) and the mean observed was per cent whereas amylopectin averaged to per cent ranging from to per cent. Study on suitability of potato varieties grown in North-eastern Indian plains for processing was undertaken by Singh et al. (2009) in West Bengal. The dry matter content of popular variety Kufri Jyoti, from different districts of West Bengal, ranged from 17 to 19.6 percent. Processing varieties Lady Rosetta, Kufri Chipsona-3, Kufri Chipsona-1 and Atlantic showed a dry matter content of 23.3, 22.8, 19.5 and 20.1 per cent, respectively, while all the other varieties, except Kufri Chandramukhi (19.2%), had dry matter content of 18.1 per cent. The reducing sugars content of processing varieties, Atlantic and Kufri Chipsona-1 was very low ( mg/100g fresh wt), while all other varieties contained higher levels of reducing sugars ( mg/100g fresh wt). Kufri Jyoti contained higher levels of total phenols ( mg/100g fresh wt), while processing varieties, Atlantic and Kufri Chipsona-1 had lower levels ( mg/100g fresh wt). Lady Rosetta contained lowest total phenols (23.6mg/100g fresh wt), whereas, Kufri Jyoti contained very high levels of phenols ( mg/100g fresh wt). Uppal (1995) experimented in Punjab and found that there was a significant varietal difference in sugar content and invertase activity at the time of storage and during storage. During storage, reducing sugar content increased about 37 per cent and invertase activities coincided with the accumulation of sugars. Sucrose content decreased during storage. Both basal and total invertase activities increased during storage, however basal activity was about 50 per cent of the total. Tubers of Kufri Sherpa contained minimum level of free sugars and invertase activity. Marwaha (1999) in Punjab studied the chipping quality and related processing characteristics of Indian potato varieties grown under short day and showed that dry matter contents of the varieties ranged from per cent with lowest in Kufri Bahar and highest in Kufri Chandramukhi, while the reducing sugar contents varied between milligram per 100 gram fresh weight basis with lowest in Kufri Sherpa and highest in Kufri Lalima. Glucose constituted the major fraction of reducing sugars in all the varieties. Kufri Jyoti had maximum content of total phenols with 49.7 mg/100 g fresh weight basis, while free amino acids were maximum in Kufri Bahar with mg/100 g.

13 Study on effect of storage environments on chip colour and sugar levels in tubers of potato cultivars was studied in Punjab. The contents of reducing sugars ranged between 188 mg and 325 mg per 100 gram fresh weight basis at the initial stage with lowest in Kufri Sherpa and highest in Kufri Jawahar. However sucrose was maximum in tubers of Kufri Sherpa with 312 mg per 100 gram fresh weight basis and maximum in Kufri Chandramukhi (198 mg/100 g) fresh weight basis. Maximum reduction (44 %) in reducing sugars was found in tubers of Kufri Jawahar and minimum (6 %) in Kufri Lauvkar, when stored at evaporative cool storage (Uppal, 1999). Ezekiel and Dahiya (2004) assessed the storage losses of potatoes stored in heaps and pits in the Malwa region (Madhya Pradesh) and found that at harvest, tuber had relatively higher dry matter content of 22.3 per cent and lower reducing sugar content of 25.1 mg/100 g fresh weight basis. The chip colour score was 3.3, which was good. After storage in heaps and pits, the dry matter content improved by 2-3 per cent due to weight loss with higher in heap storage method (25.2 %) and the reducing sugar content remained within the acceptable limit (36.7 mg/100g) on fresh weight basis. Peschin (2000) studied the influence of storage temperature and reconditioning on the biochemical composition of potato tubers in Himachal. There was no significant varietal difference among genotypes in their biochemical constituents at the time of storage and during storage. Among these Kufri Kuber, Kufri Chandramukhi and Kufri Lauvkar contained low reducing sugars of 1.8, 5.8 and 5.0 mg/100 g fresh weight basis respectively. On storage at 5-7 C, all the cultivars showed accumulation of large quantities of reducing sugars and phenols and produced dark brown coloured chips. All the genotypes reflected an accumulation of phenols, which was more predominant after 90 days of storage. Post harvest reconditioning of tubers for 10 days at ambient temperature (20±2 C) caused decline in reducing sugar and phenolic contents in all the cultivars. However, it was ineffective as a means of lowering free amino acids content and there was no significant improvement in chip colour. A study was undertaken to determine the cooking quality characteristics of advanced clones and potato cultivars by Hassanpanah et al. (2011) in Iran under invitro conditions. There were significant differences between cultivars and clones for tuber yield, dry matter, starch percent, specific gravity, French fry and chips colour, quality and amount of reducing sugars. The , , clones and Savalan cultivars had the highest yield i.e , 49.11, and (t ha -1 ) respectively. Dry matter (22.52%), specific gravity (1.91%) and starch (16.62%) content were highest in Savalan variety among the three cultivars whereas clones had the highest dry matter (24.4%). Specific gravity (1.100) and starch (17.69%) were highest in among the clones. Uppal (2000) documented chip colour and processing parameters of potatoes grown during spring and autumn in north-western plains in Punjab. The reducing sugar content of both Kufri Chandramukhi and Kufri Jyoti varieties were much low, 67 to 89 mg/100g fresh weight basis in spring as against 289 to 304 mg/100g in autumn. But Kufri Chandramukhi contained high amount of reducing sugars and total sugar, in both the seasons. Effect of location, season and cultivar on the processing quality of potatoes was investigated by Kumar et al. (2003) in Uttar Pradesh. An average dry matter content of 20% and above was observed for tubers grown at Deesa, Dhali,Jorhat,Kota,Chindwara and Taizabad. Among several locations, reducing sugar content was highest in Kufri Sutlej ranging from 74.7 per cent to per cent mg/100g fresh weight basis. The sucrose content was below 200 mg/100g tuber fresh weight at Jorhat, Kota and Chindwara. Evaluation of potato cultivars for processing into potato crisps was carried out by Abong et al. (2010) in Kenya. Most cultivars with exception of six of them including Roslin Tana, Desire, Roslin Ebura, Nyayo, Tigonilong and Kihora had acceptable physical characteristics suitable for processing. Tuber diameter varied significantly (p 0.05) among the cultivars ranging from 43 mm in Tigoni long to 56 mm in Kenya Sifa and Clone The specific gravity of the cultivars varied from to and dry matter contents from per cent to per cent. With exception of Roslin Tana, Desire, Roslin Eburu, Nyayo and Tigoni Long which had long or pointed oval shapes, majority of the cultivars were round in shape. Reducing sugar levels significantly (p<0.05) varied among the cultivars and ranged between 0.07 per cent and 0.4 per cent.

14 With an effort to develop a processing potato variety suitable for growing in high lands, a study was conducted in Himachal Pradesh by Pandey et al. ( 2008). The round oval tubers had high dry matter (22.4%), low reducing sugar (<100 mg/100g fresh weight basis) with less than 250 mg/100 gram of sucrose on fresh weight basis. Marwaha et al. (2008) undertook the effect of blanching of slices of potato varieties on chipping quality in Punjab. Dry matter content ranged from 15 per cent (Kufri Pukhraj) to 23.4 per cent (Kufri Chipsona-2). Kufri Chipsona-1 and Kufri Chipsona-2 contained high tuber dry matter i.e. >21%, while Kufri Pukhraj contained minimum dry matter (15%). Starch content, yield and quality of dehydrated chips were investigated in Patna. Varieties Kufri Chipsona-1 and Kufri Chipsona-2 had higher dry matter content of 21.2 per cent and 22.0 per cent respectively. There was no significant difference in the moisture content of dehydrated chips. The peeling loss was also low in both Kufri Chipsona-1 (11.3%) and Kufri Chipsona-2 (11.9%) respectively (Das et al., 2001). Marwaha et al. (2009) researched on Indian and exotic potato processing varieties for storage behaviour and changes in nutritional compounds under different condition. Indian and American processing varieties having high dry matter content viz. Kufri Chipsona-1, Kufri Chipsona-2, Atlantic and Frito Lay produced high chip yield 30.4 per cent per cent with low oil content (<35%). Both Indian and American processing varieties contained ( >22%) dry matter, while Kufri Jyoti showed lowest dry matter content before 17.2 per cent and after storage 19.6 per cent and 18.4 per cent under both storage condition. Investigation on impact and future priorities of potato processing varieties was carried out by Pandey et al. (2009) in Himachal Pradesh. Processing varieties Kufri Chipsona-1, Kufri Chipsona-2, Kufri Chipsona-3 produced high yield >30 t/has with dry matter content of 21 per cent 24 per cent, reducing sugars of < 0.1 per cent, low phenols and glycoalkoloids. A study conducted on low and high sugar potato cultivars for processing qaulity as influenced by storage temperature by Marwaha (2000) in Punjab. The dry matter content of exotic cultivars was higher than the Indian cultivars and free amino acids and total phenols were significantly lower in the exotic cultivars than the Indian cultivars at the time of storage. The reducing sugar content of the exotic cultivars was very low (64-80 mg/100g fresh wt basis) as compared to the Indian cultivars ( mg/100g fresh wt basis). Abong et al. (2009) experimented on Kenyan cultivars to observe the influence of potato cultivar and stage of maturity on chips and French fries. Dry matter content ranged from per cent to per cent and per cent to per cent in clone and variety Dutch Robyjn for tubers harvested 90 and 120 days after planting, respectively. A study on potato varieties grown at different locations for chipping was done by Uppal and Khurana (2001) in Punjab. The chip quality and contents of dry matter and free sugars varied among varieties and locations. Potatoes grown at Bhubeneswar, Chhindwara, Deesa, Kota and Patna had low concentration of reducing sugar ranging from (0.13%) to (0.24 %) on fresh weight basis. The amount of reducing sugars was much more than the permissible limits (0.29% to 0.4%) for processing at Faizabad, Muzaffarbad, Hisar, Jalandhar and Udham Singth Nagar. A study was carried out on the effect of chemical composition of potato on crisps Kita (2002) in Poland. The contents of dry matter, starch and protein nitrogen ranged from per cent to per cent, 15.2 per cent to 18.4 per cent and per cent to per cent respectively. A study was conducted to determine the chemical composition of six potato varieties by Basuny et al. (2009) in Egypt. Among the varieties, Valour had the highest moisture (83.27%) and lowest in Osina (75.53%) whereas protein (2.73%), ash (0.97%) and carbohydrate (18.70%) were highest in Osina variety. A study was undertaken on MP/97-644: A promising hybrid for making potato chips and dehydrated products in Uttar Pradesh. The hybrid MP/ gave significant higher total tuber yield, dry matter, low reducing sugars, amino acids and showed round shape with shallow eyes making it suitable for chips preparation (Singh et al. 2005).

15 Tuber with bigger size is better for processing as well as for export as it contents low reducing sugar and phenols. Compared to peel, tuber posses greater values of energy and total carbohydrates whereas peels considerably rich in crude protein, crude fibre, minerals matter, insoluble minerals, reducing sugar, total fructose, non reducing sugar and free amino acid. The contents of biochemical metabolites in tubers differ with the cultivars and growing location. Among the Indian cultivars Kufri Chipsona-1 and Kufri Chipsona-2 were rich in dry matter and suitable for processing with low content of reducing sugar. 2.2 PROCESSING AND SCREENING OF POTATO VARIETIES The potato processing industry is primarily concerned with the quality and yield of processed products. The processing quality, in turn, is a function of physical and chemical factors. Screening of potato varieties help the processing industries to pick appropriate tubers with low reducing sugar and moisture, high dry matter as well as impart acceptable colour and flavour to the processed products. Singh et al. (2005) in Uttar Pradesh carried out a study on MP/97-644: A promising hybrid to assess the processing quality parameters of tubers during storage at C with Isopropyl N-(3-chlorophenyl) carbamate (CIPC) application in a commercial cold store for six months. The hybrid MP/ gave significant acceptable chip colour (grade<3) over the control at all locations and better than the exotic variety Atlantic, thereby assuming higher economic returns to the farmers as well as the processors. Effect of blanching of slices of potato varieties on chipping quality was studied by Marwaha et al. (2008) in Punjab. Peeling loss of the tubers from different varieties varied between 8.9 per cent and 10.5 per cent. Kufri Chipsona-1 and Kufri Chipsona-2 produced more chips both from blanched and unblanched slices >29%, while Kufri Pukhraj produced least chips of 22.6 per cent and 23.1 per cent from blanched and unblanched slices respectively. Blanching significantly (p<0.05) reduced the mean chip yield. Blanching improved the chip colour significantly (p<0.05) in all the varieties. Blanching reduced the content of reducing sugars, sucrose, free amino acids, total phenols, ortho-dihydroxy phenols and tyrosine by 46.9, 40.7, 55.3, 37.6, 37.8 and 29.8 per cent respectively. Joshi and Nath (2002) investigated the effect of pre-treatment on quality and shelf life of fried chips from sprouted tubers of potato variety Kufri Chandramukhi in Pantnagar. Sensory evaluation of mm thick slices from unpeeled sprouted tubers treated with citric acid, sodium chloride and calcium chloride and conditioning (195 C) for 17 seconds yielded best quality chips. Chips from peeled potatoes and unpeeled potatoes did not differ significantly. Yield and quality of dehydrated chips and starch content was investigated by Das et al. (2001) in Patna. Varieties Kufri Chipsona-1 and Kufri Chipsona-2 produced higher chip yield of 14.3 per cent and 15.3 per cent respectively. There was no significant difference in the moisture content of dehydrated chips. The peeling loss was also low in both Kufri Chipsona per cent and Kufri Chipsona per cent respectively. The quality of dehydrated chips prepared from Kufri Jyoti and Kufri Sindhuri were also comparable to other two varieties. Suitability of potato varieties grown in North-eastern Indian plains for processing was assessed. Varieties Kufri Chipsona-1 and Atlantic produced chips of excellent colour quality with colour score between 1.75 to 2.75 in both 2006 and 2007 year, while Lady Rosseta collected during 2007, also produced chips of very good quality. Chip yield varied between 27.4 to 28 per cent in Kufri Chipsona-1 and Atlantic during 2006, while it ranged from 28.1per cent to 32 per cent in Kufri Chipsona-1, Kufri Chipsona-3, Atlantic and Lady Rosseta (Singh et al., 2009). Nutritional losses of dehydrated chips and cubes from potato cultivars viz. Kufri Jyoti and Kufri Chandramukhi in Himachal Pradesh was determined by Rani and Ezekiel (2003). Nutritional losses varied from 73 per cent to 86 per cent in dehydrated chips and 71 per cent to 78 per cent in dehydrated cubes. Maximum loss of 77 per cent to 86 per cent was observed in soluble protein and the loss in reducing sugar was73 per cent to 81 per cent. Minimum loss of 73 per cent to 74 per cent was observed in free amino acids. Nutritional value of potato chips of different brands available in the market was quite low compared to that of raw potatoes with nutritional losses varying from 16 per cent to 98 per cent (Rani and Ezekiel, 2003).

16 Raj and Lal (2008) studied the effect of cultivars, cold storage and frying media on yield and processing qualities of potatoes in Solan. Maximum yield of chips 30.5 per cent was obtained in Kufri Chipsona-1 followed by Kufri Chipsona per cent and minimum in Kufri Jyoti 27.4 per cent followed by Kufri Badsha 28.5 per cent. Minimum oil absorption was observed in Kufri Chipsona per cent and maximum in Kufri Bashah 44.5 per cent. Moisture content of the fried chips ranged between 1.6 per cent in Kufri Chipsona-1 and 3.2 per cent in Kufri Badshah. Cultivars with high dry matter and low moisture produced chips with low moisture levels. The colour and texture of the chips of Kufri Chipsona-1 and Kufri Chipsona-2 were the best. Suitability of cultivars, frying medium and packaging for potato chips was assessed in Ludiana. Kufri Jawahar had the most desirable quality characteristics and produced the best quality chips among the cultivars used. The highest consumer preference for potato chip frying medium was for cotton seed oil followed by sunflower oil. The highest yield was obtained from cultivar Kufri Jawahar and the lowest yield in case of Kufri Chandramukhi. The best colour of the chips was observed in Kufri Jawahar, Kufri Badsha and Kufri Jyoti while Kufri Chandramukhi gave chips of dark brown colour. The chips produced from Kufri Jawahar had lowest moisture (1.18%) and oil uptake (34.04%). Whereas Kufri Chandramukhi produced chips with highest moisture (9.27%) and oil uptake (39.71%) as reported by Sandhu et al. (2002) Indian and exotic potato processing varieties were evaluated for storage behaviour, processing quality and changes in nutritional and antioxidant compounds under different condition by Marwaha et al. (2009). Indian and American processing varieties having high dry matter content viz., Kufri Chipsona-1, Kufri Chipsona-2, Atlantic and Frito Lay produced high chip yield 30.4 per cent per cent with low oil content (<35%). Compared to peeling losses before storage, the peeling losses of tubers after storage were 4.3 per cent and 2.8 per cent higher in farm and evaporative cold stores respectively. Chip colour produced by Atlantic variety was most acceptable (3.5) compared to other varieties. Gaur et al. (1998) screened Kufri Chipsona-1 variety for processing. Kufri Chipsona-1 had 2 per cent to 4 per cent higher tuber dry matter than Kufri Jyoti. It also produced acceptable light colour chips of grade 1-3. In contrast, Kufri Jyoti produced unacceptable brown colour chips of grade 5-6. But chip yield from Kufri Chipsona-1 as well as Kufri Jyoti were per cent and per cent respectively. Sandhu and Parhawk (2002) studied the suitability of different potato cultivars for the preparation of dehydrated potato cubes. Blanching of 1 cm 3 size in boiling 2.0 per cent brine solution for 3 minutes followed by dipping in 0.2 per cent solution of potassium metabisulphite for 10 minutes was the best pre-treatment. Among the four drying methods, drying by combined microwave for 17 minutes followed by cabinet drying at 90 ± 5 C for 3 hour produced the best quality dried potato cubes. The score for appearance, flavour, texture and overall acceptability was maximum for combine microwave and cabinet drying (8.48 and 8.20) respectively. The acceptability of dehydrated potato cubes from Kufri Jawahar was better (8.62) than Kufri Jyoti (8.37) for all drying methods. Ezekiel and Rani (2006) investigated the shelf life of potato chips during storage. The dry matter content of tubers of thirty three potato genotypes varied from (16.3%) to (26.2%). Oil content showed a highly significant negative relationship with tuber dry matter content (r= 0.87**) and starch content (r=-0.86**), however no relationship with amylase content (r = ) and swelling volume of starch was found. A study was undertaken on effect of frying oil temperature on quality and yield of potato chips. Frying at 170 C for 6 mn gave potato chips of most acceptable qualities, which had 1.1 per cent moisture and 38.5 per cent oil content. Decrease in yield when temperature was raised from 160 C to 170 C was more than decrease in yield when temperature was raised from 170 C to 180 C at any given frying time (Nema and Prasad, 2004). Mahmood et al. (2006) examined the effect of common household cooking methods on resistant starch of roots and tubers in Mumbai. The resistant starch content of raw roots/tubers varied from 1.1 per cent to 2.9 per cent fresh weight basis. Boiling of all roots/tubers increased the resistant starch content, the increase being highest for potato (28.8 %) and least for sweet potato (7.2 %). Pressure cooking of potato and sweet potato increased resistant starch by (18.9%) and (11.3 %) respectively. Refrigeration of pressure cooked

17 potato at 4 C for 12 hour increased resistant starch content by 55 per cent. Sautéing followed by cooking reduced resistant starch content by 45.8 per cent in colocasia and 55.5 per cent in elephant yam. Frying of potato decreased resistant starch content, maximum decrease being with shallow frying. Pandey et al. (2009) investigated the impact and future priorities of potato processing varieties in Himachal Pradesh and concluded that all the processing varieties Kufri Chipsona- 1, Kufri Chipsona-2, Kufri Chipsona-3 produced imparted < 5% per cent undesirable colour and <15 % total defects in chips when grown at different locations in India. A study was done on processing quality of low and high sugar potato cultivars as influenced by storage temperature by Marwaha (2000) in Punjab. Before storage, fresh fried chips prepared from exotic cultivars were for superior in colour i.e. 1,1,2,1,1 in Atlantic, FL 1291, FL 1533, FL 1584, FL 1625 respectively in comparison to Indian varieties with 5,5,3 colour score for Kufri Chandramukhi, Kufri Jyoti and Kufri Lauvkar respectively. High temperature storage up to 75 days was found to be suitable for producing chips of acceptable light colour from all the exotic cultivars, while only one Indian variety, Kufri Lauvkar, performed well that grown under short day condition. Pokharkar and Mahale (2001) studied the optimization of processing variables for preparation of fresh fried chips by developing regression equation. The loss of reducing sugars have an average diffusivity of 5-01X10-9 m 2 /s in case of blanching of 1.5 and 2.0 millimetre thick slices in boiling water. For good quality potato chips, the optimum parameters including frying time; seconds, oil temperature ; C and thickness of slices ; 2.0 mm by linear programming technique. The colour score of chips from 7 to 9 were acceptable by consumers. Chips with scores less than 7 and more than 9 were unacceptable. A study was carried out on chipping quality and related processing characteristics of Indian potato varieties grown under short day conditions by Marwaha (1999) in Punjab. Fresh fried chips prepared from two varieties viz., Kufri Sherpa, Kufri Lauvkar were light in colour with colour score 2 and 3 respectively and were acceptable, whereas other eight varieties gave a unacceptable colour score ranging from 6 to 8. However, when morphological characters such as tuber size and shape were taken into consideration, only Kufri Lauvkar was found most suitable for chipping. Barba et al. (2008) investigated the phenolic constituents level in peeled and unpeeled cultivar, Agria potato under microwave processing in Italy. Baking time increases with the decreasing of the power level, but at the same time, reduced water losses, due to a slower heating. Baking time in microwave was shorter when compared to traditional boiling method. The boiling method resulted in higher loss of protocatechuic acid and tryptophan content of 85.6 per cent and 94.8 per cent respectively when compared to microwave baking in peeled samples. The unpeeled samples showed a better preservation of these compounds. The best time and reduced water as well as phenolic losses is obtained using 500 watt as power input. Comparison of the volatile components of eight cultivars of microwave baked potato was studied by Oruna-Concha et al. (2002). Lipid degradation, maillard reaction and sugar degradation were the main sources of the eighty flavour components identified. The grand total amount of all categories of compound was lowest for Cara and highest for King Edward variety. Cara contained the lowest amount of maillard derived compounds while Marfona contained the highest amount. Amount and relative abundances of sulphur compounds were lowest in Fianna (0.3%) and highest in Nadine (29.4%). Terpenes were lowest in Desiree and highest in Pentland squire, relative abundances ranging between (1.0%) and (16.4 %) for the cultivars. Barry-Ryan et al. (2010), investigated differences in the physicochemical and sensory properties of organic and conventional potatoes (cv. Orla) in Ireland. The conventional potatoes had a lower dry matter content (P < 0.05) and a slightly softer texture (P < 0.05) than the organic potatoes. The conventional baked potato was slightly softer, less adhesive and wetter than the organic baked potato (P <0.05). There was no significant difference between the organic and conventional baked potato samples for the sensory attributes of appearance, aroma, texture, taste and acceptability..

18 The influence of potato cultivar and stage of maturity on chips and French fries was experimented using eight Kenyan cultivars in Kenya including five varieties and three promising potato. Potato tubers differed in oil content absorbed which ranged from 8.55 per cent to per cent and 6.4 per cent to 9.82 per cent in Dutch Robyjn and Desiree for tubers harvested 90 and 120 days after planting, respectively. The variety of potato used had a significant effect (P 0.05) on oil uptake, with Dutch Robyjn having the lowest oil content. Harvesting before maturity increased oil content of chips significantly (P 0.05) when compared to those prepared from mature tubers. The sensory attributes for each separate harvest indicated that there were significant (P 0.05) differences in scores for colour, texture, flavour, oiliness and overall acceptability in French fries made from different cultivars in both harvests (Abong et al., 2009) With an effort to develop a processing potato variety suitable for growing in highlands, a study was conducted in Himachal Pradesh by Pandey et al. (2008). The variety Kufri Himsona produced high yield and good processing grade tubers. The colour of the chips produced from Kufri Himsona was light and acceptable (<3.0). None of the varieties produced acceptable colour chips. Uppal and Khurana (2001) researched on chipping performance of potato varieties grown at different locations in Punjab. Potatoes grown at Bhubeneswar, Chhindwara, Deesa, Kota and Patna produced acceptable chips of golden yellow colour with colour score 4.7, 4.0, 4.2, 3.6 and 4.3 respectively. The tubers grown at Faizabad, Muzaffarbad, Hisar, Jalandhar and Udham Singth Nagar were unfit for making chips and produced chips of darker colour ranging from 6.3 to 9.7 colour score. A study on comparative oil uptake by potato chips during frying under different conditions was undertaken by Berry et al. (1999) in Punjab. The oil uptake expressed as oil uptake ratio in chips fried in different frying media ranged from 0.34 to 0.41 with lowest ratio in groundnut oil and highest in soybean oil. Higher initial temperature of frying media, in general resulted in increased oil pick up by the chips. Carboxymethyl cellulose (0.1%) was found to be effective in reducing oil uptake. The moisture content in chips found highest when fried in vanaspati (1.7%) and least when fried in cotton seed oil (1.3%). Chips fried in cottonseed oil picked up less oil remained crisp and retained better quality during storage. Pedreschi et al. (2007) in US investigated the effect of only blanching and blanching plus NaCl impregnation on the physical properties of the potato chips. The moisture loss profile was similar for chips pre-treated in the two ways i.e. blanching and blanching plus NaCl impregnation during frying. Oil uptake increased up to approximately (20 %) as the frying temperature decreased; soaking of blanched chips in the sodium chloride solution decreased slightly the oil absorption of approximately (7 %). Soaking of blanched slices in the sodium chloride solution produces paler chips compare to control chips after frying. Soaking in sodium chloride of blanched chips increased its crispness after frying at 120 C, 140 C, 160 C and 180 C in (15%), (13%), (11%) and (11%) respectively. A comparative study of physical and sensory properties of pre-treated potato slices during vacuum and atmospheric frying was conducted by Troncoso et al. (2009) in Chile. Vacuum frying increased significantly (p<0.05) oil content and decreased instrumental colour and textural parameters. Potato slices fried under vacuum had better colour readings significantly higher compare to the slices fried under atmospheric conditions. Sensory attributes, flavour quality and overall quality, were significantly improved using vacuum frying. The higher frying temperature (140 C) increased colour, breaking force, hardness and crispness. A great improvement on colour parameters was obtained using sulphited potato slices instead of the other pre-treatments. Although, the better flavour was obtained for control potato chips, no significant differences were found for overall quality between control and sulphited potato chips. Significant correlations (p<0.01) between sensory and instrumental responses were found. Moyano and Pedreschi (2005), in Chile experimented on kinetics of oil uptake during frying of potato slices and effect of pre-treatments. Oil uptakes in fresh, blanched and dried slices were studied during frying. Oil uptake was high even for short frying time at the different temperatures tested. For control slices, oil uptake increased approximately by (32 %) as the frying temperature decreased from 180 C to 120 C at moisture contents 1 g water/ g dry solid.

19 The oil content average values were 0.39, 0.35 and 0.30 g/g dry basis at 120 C, 150 C and 180 C respectively. No apparent effect of frying temperature in oil uptake was observed at moisture contents 0.5 g water/ g dry solid in fried slices previously blanched and dried. Study on effect of pre-drying on texture and oil uptake of potato chips was undertaken in Chile by Pedreschi and Moyano (2004). Texture analysis revealed that final maximum force was significantly higher (p>0.05) for blanched and dried potato chips than for only blanched potato chips. Both frying temperature and pre-drying temperature had a significant effect (p>0.05) over the final texture and oil content of the fried potato chips. When fried at 120 C, potato chips containing moisture <10g/100g were crispier and contained more oil than potato chips fried at 180 C. Pre-drying dramatically decreased the oil absorption and significantly increased (p>0.05) the crispness of the blanched potato slices after frying. Duran et al. (2006) studied the effect of pre treatments and oil temperature on oil partition in Chile. During frying, potato chips absorbed nearly 38 per cent of the total oil content, and majority of it remained at the chip surface without penetrating into the microstructure. During cooling stage it was reverse and approximately 65 per cent of the total oil content was absorbed by potato chips and only 35 per cent remained at the chip surface. Whereas potato chips coated with the edible film hydroxypropylmethylcellulose absorbed significantly (p<0.05) more oil than control and salt impregnated potato chips. With an aim to develop a reference colour chart for potato chips from fresh and stored potatoes, a study was conducted by Ezekiel et al. (2003) in Himachal Pradesh. Increasing colour scores showed a significant positive correlation (r= 0.77**) with reducing sugar content of tubers. Tubers with reducing sugar content ranging from mg/100g fresh weight produced chips of colour score 1, whereas tubers with reducing sugar content of mg/100g fresh weight produced chips of colour score 5. Research on chip colour and processing parameters of potatoes grown during spring and autumn in north-western plains was studied by Uppal (2000) in Punjab. Chips made from tubers of spring crops were of light yellow colour (2-3 scores), superior in taste and highly acceptable, whereas autumn crop potatoes produced unacceptable chips having dark brown colour (6-7 scores). Kumar et al. (2003) investigated the effect of location, season and cultivar on the processing quality of potatoes was investigated in Uttar Pradesh. An average chip colour score of less than 4 was observed from the potatoes procured from Deesa, Dhali, Jorhat and Kota. Potatoes from Jorhat gave most consistent results. A study was conducted in Peradeniya on eleven locally available potato varieties to investigate their suitability for chipping. The total sugar content increased and the dry matter content decreased during storage of the tubers. The chip lightness L value showed a negative relationship with total sugars. The colour of the chips made from Asteric, Atlantic, Desiree and Red Star was acceptable and was not affected by three months storage. Whereas Escort, Granola, Monolize, Prelude, Sita, Vivald and Aranka did not produce chips of acceptable colour. Hot water blanching at C for 1 minute with 200 ppm KMS improved the chip colour of Escort, Prelude, Sita and Vivaldi varieties. The residual sulphur dioxide content of these chips was 45 ppm. Chip colour of Monoliza, Granola and Aranka, varieties was not improved even by the KMS treatment (Illeperuma and Wickramasinghe, 2000). The effects of various preparation technologies on the proximate composition and energy content of potato products were investigated by Ramaswamy et al. (1999) in Mauritius. Result shows that various preparation technologies viz., boiling, baking, frying of chips and frying of battered cakes have a significant effect (P < 0.01) on the proximate composition and energy content of potato products. A general decrease in moisture, fibre, carbohydrate and protein was noted for most of the preparation technologies. The ash content of processed products 5, 4.7, 9.5 g/100g dry weight basis for boiled potato, baked potato and chips respectively compared to raw potato (4.4 g/100 g dry weight basis) with the exception of battered cakes. In frying chips and battered cakes, the fat as well as energy contents were significantly higher (P < 0.01) compared to boiling and baking. Compared to raw potato, drastic increase in fat contents of 9795 per cent and 9321 per cent were observed during frying of chips and battered cakes respectively.

20 Basuny et al. (2009) conducted the study to determine the relationship between the sensory evaluation of potato chips and chemical composition of six potato varieties in Egypt. Organoleptic evaluation for fried potato chips in sunflower oil indicated that Osina, Sponta and Glactica potato varieties are suitable for frying process as judged by the taste panelists. The highest oil uptake by chips from varieties viz., Valour, Ledy valour and Hana potato was evident. Chips produced from Osina, Sponta and Glactica potato varieties had lowest oil uptake. Hassanpanah et al. (2011) studied the cooking quality characteristics of advanced clones and potato cultivars in Iran under invitro conditions. These cultivars were suited for C type cooking and thus clone and Savalan cultivars were appropriate for chips production whereas clone for French fry, chips and starch production. The Marfona cultivar with lower dry matter content per cent and B cooking type was suitable for consumption of boiled and mashed tuber. A study was carried out by Jansky (2008) in USA to determine the relative contributions of genotype and environment to baked potato flavour variation in standard potato cultivars. In addition, relationships between individual flavour components and overall quality perception scores were determined. Differences among cultivars and production environments were found. Stored potatoes received higher quality perception scores than fresh potatoes. Mealiness was the most variable flavour attribute and was influenced by both genotype and environment. Sweetness and flavour intensity were positively associated with quality perception. A strong negative association between offflavour and quality perception was also detected. Kita (2002) investigated the effect of chemical composition of potato on crisps in Poland. The crisps made of Aster, Karlena, Saturna and Panda varieties were characterised by an appropriate golden-yellow colour, typical flavour and odour, a slightly darker colour produced from Ania potato variety. The Ania variety with more reducing sugar (0.13%) produced darker colour crisp. The highest fat content was in crisps made of the Aster potato variety per cent, while those produced from the Panda variety had per cent of fat. The highest score was given to texture of crisps made from the Panda and Saturna potato varieties. Worse textures were produced from the Aster and Karlena tubers and the worst from the Ania potato variety. Apart from starch and protein nitrogen, the crisp texture was also influenced by non-starch polysaccharides which contributed to the extent of (9-21%) towards crispness in the model. Sensory quality of multiple potato genotypes following three methods of preparation was studied in Ohia state university US. Under microwave cooking, best scores was rated for Russet Norkotah, Katahdin and AF and worst score for NY 112. Highest score for the varieties prepared on a convention oven was obtained by B1829-5, NY 112 and Katahdin and least score by Dakota Rose variety. Among the varieties prepared by boiling, highest rate was scored by Kennebec, AF and NN19525 and least rate by B variety (Kleinhenz et al., 2003). Mestdagh et al. (2008) in Belgium documented the impact of chemical pre-treatment on the acrylamide formation as well as sensorial quality of potato crisps. The oil content was highest in crisps which were blanched in water alone (40%) whereas least when crisps were blanched along with the component Ca100 and 23 per cent. The addition of calcium provoked a more crispy texture i.e. CaCl2 (snap, 9.1; crispness, 9.1), Ca100 (snap, 9.1; crispness, 8.9) and Ca200 (snap, 8.7; crispness, 9.0) compared to the control crisps (snap, 6.7; crispness, 6.8). A significant correlation was found between both textural descriptors, snaps and crispness, as well as between the taste and general appraisal. Effect of oils and frying temperature on the texture and fat content of potato crisps was investigated by Kita et al. (2007). The crisps fried in rapeseed oil absorbed the smallest amount of fat (36.8%) irrespective of frying temperature, whereas the crisps fried in olive oil and modified oil II (hydrogenated with mixture of rape seed oil and palm oil) absorbed the highest quantity of fat (41%). Significant differences in fat content of potato crisps fried in rapeseed and olive oils were observed at frying temperatures of 150 C, 170 C and 190 C. Crisps fried at 150 C in rapeseed and peanut oils exhibited more hard and less crispy textures. Most variable texture was in crisps fried in olive oil i.e. hardest at lower (30.26N) and crispy at highest (15.43 N) frying temperature. Except for olive oil there was no significant difference between textures of crisps fried at 190 C and 170 C. Type of oils used and frying temperature markedly affected fat content and texture of potato crisps.

21 Abong et al. (2010) evaluated the potato cultivars for processing into potato crisps in Kenya. The sensory attributes of potato crisps that were evaluated differed significantly (p 0.05) among the cultivars. Variety Roslin Eburu had the highest colour score (5.68) while Cangi had the lowest score (2.73). The low score for flavour was exhibited by Cangi (3.41) whereas highest score for texture was exhibited by Roslin Eburu (5.41) and lowest by Cangi (3.32). Dry matter content, free sugar content and chip quality of tubers is influenced by variety and location. Dry matter (starch, sugars, protein nitrogen, non poly saccharides and minerals etc.), low moisture, blanching and pre treatments affects the processing quality. Blanching significantly reduced mean chip yield but improved the chip colour whereas blanching and dehydration reduced the chemical and nutritional composition. Frying potato slices at 170 C for 6 minute produced potato chips of most acceptable qualities. Oil uptake increased as the frying temperature decreased but slightly decreased when blanched chips were soaked in the sodium chloride. And this oil content of chips showed a highly significant negative relation with tuber dry matter content and starch content. Soaking slices in sodium chloride also increases the crispness. Texture of chips is one of the important characteristic which is influenced by the starch and protein nitrogen content but apart from this, it is also affected by non starch polysaccharides. Colour is one of the significant parameter and has a significant positive correlation with reducing sugar content of tubers. Baking time increases with decrease of power level but at the same time reduces water losses whereas boiling results in higher loss of phenolic constituents compared to the microwave baking. The mineral content increases when potato is boiled, baked or fried.

22 3. MATERIAL AND METHODS Potato, as a genus (Solanum) differs in varieties from one another in morphology and chemical composition of plant and tubers which affects the yield and quality of the processed products. Thus the study on Screening of potato varieties for chemical composition and processing was undertaken during August Ten varieties of potato tubers namely- Kufri Chipsona-2, Atlantic, Kufri Surya, Kufri Khayti, Kufri Jyoti, Kufri Pushkar, Kufri-Bahar, Kufri- Ashoka, J/99-24 with Kufri Pukhraj as control were procured from All India Coordinated Research Project, Kumbapur farm, Dharwad, Karnataka. In accordance with the objectives, the research methodology on analysis of physico-chemical composition and suitability of potato varieties for processing into different products has been presented here under. 3.1 Collection of potato tubers 3.2 Physico-chemical composition of potato tubers Physical characteristics of potatoes Chemical composition of potatoes 3.3 Optimization of processing of potato products Preparation of chips Cooking of potatoes by different methods 3.4 Screening of potatoes for processed products Potato chips Cooked potato (Baked and pressure cooked) 3.5 Organoleptic evaluation of processed products Total score Acceptability Index 3.6 Statistical analysis 3.1 COLLECTION OF POTATO TUBERS Well cured potato tubers harvested in October, 2010 were collected and stored in aerated trays. A total of ten potato cultivars of first picking viz., Kufri Chipsona-2, Atlanta, Kufri Surya, Kufri Pukhraj, Kufri Khayti, Kufri Jyoti, Kufri Pushkar, Kufri Bahar, Kufri Ashoka and J/ were analysed for different physico-chemical attributes and processing quality (Fig.1). 3.2 PHYSICO-CHEMICAL COMPOSITION OF POTATO TUBERS Physical characteristics of potatoes Physical characteristics of the agricultural produce are the most important parameters in the design of grading, handling, processing and packaging system. Physical characteristics namely weight, volume, specific gravity, diameter, size, shape, colour, acceptability, visual observation of skin and flesh colour of 10 potatoes varieties were recorded. Every fifth sample comprising of ten tubers from each variety were picked and studied Weight Weight (g) of 10 potato samples from each variety measured to two nearest decimals were taken and mean weight for the variety was obtained Volume Volume of selected 10 potato samples were measured by water displacement method. Volume (cc) of potato tubers was calculated as below and average was taken (Tabatabaeefar, 2002).

23 Volume (cc) = Volume of water with potato (cc) - Volume of water without potato (cc) Specific gravity Weight of each potato sample in the air and weight of water displaced by the same potato was recorded. Specific gravity was calculated using the formula and mean value was expressed (Tabatabaeefar, 2002). Weight in air (g 1 ) Specific gravity = Diameter Weight of water displaced (g 2 ) Ten representative samples of uniform shape from each variety were picked. Circumference for each sample was measured using thread of one mm width across length and breadth of the tubers. Diameter was calculated using the formula and mean diameter was obtained Size Circumference (cm) Diameter (cm) = π (3.14) A total of 100 potato samples with 10 each from 10 varieties were used to obtain the mean size. Length (cm) and breadth (cm) of each potato sample was measured using vernier calliper and mean tuber size was obtained Shape Ten representative tubers from each variety were observed for different shapes viz., round, oval and misshapened and categorised accordingly (Abong et al., 2010) Skin colour Every tenth sample of potato was randomly picked and the skin colour of the tuber was recorded as brown, brownish yellow and creamish yellow (Abong et al., 2010) Total potato defects (TPOD) Total potato defects was examined externally in terms of presence of green tint, scars, natural depression, skin texture and number of eyes. Internally TPOD of cut potatoes was visualised for presence of hollow hearts and black spots (Singh et al., 2005) Acceptability Based on number of eye depths, size, shape and appearance, the representative potato samples from each variety were classified as highly acceptable, acceptable, less acceptable and unacceptable Flesh colour From each variety ten representative samples were cut and the flesh colour was observed and recorded as cream, yellowish cream, white, creamish yellow (Abong et al., 2010) Chemical composition of potatoes Chemical composition of potato tubers is highly differentiated. The chemical constituent of potato tuber determines its suitability for processing into different products. The following chemical constituents namely: total starch, total sugar, reducing sugar, moisture and dry matter were analysed in triplicates on fresh weight basis.

24 Moisture To estimate the moisture content of raw potato five g of tuber was dried in hot air oven at 75 C till two concurrent readings were obtained (Anon., 1970). Moisture content of fried chips were estimated following the above procedure. The per cent moisture was calculated using the formula, Initial weight (g 1 ) Final weight (g 2 ) Moisture content (%) = X Total starch by Anthrone method Weight of the sample 0.1 to 0.5g of the fresh sample was homogenized in hot 80% ethanol to remove sugars. It was then filtered and the residue retained. The residue was washed repeatedly with hot 80% ethanol till the washings did not give colour with Anthrone reagent. Residue was dried over water bath.5ml of water and 6.5ml of 52% perchloric acid was added to the residue for extraction at 0 C and the filtered supernatant was saved. Extraction was repeated using fresh perchloric acid. Supernatant liquids were pooled and the volume was made up to 100ml. From this, dilution was made in the ratio 1:5 using distilled water. 0.1 and 0.2ml of this diluted supernatant was pipette into test tubes and volume was made up to 1ml with distilled water. 4ml of Anthrone reagent was added to each test tube and heated for about 8min in boiling water bath. It was rapidly cooled and intensity of green to dark green was read at 630nm in a colorimeter. A series of standards using glucose (0 to 500µg) were run and standard curve was plotted. The glucose content in the sample was estimated using the standard graph, and then the value is multiplied by a factor 9 to arrive at the starch content (Sadasivam and Manickam, 1992).

25 Starch content (%) = Glucose content (%) x Reducing and total sugars Three gram of potato sample was used to extract, one gram each from three potatoes of same variety. The potato tubers were cut into small pieces and plunged immediately into boiling alcohol. The tissue was extracted in a boiling water bath, cooled and the extract was passed through double of muslin cloth. The pieces of the tissue were homogenized thoroughly in a mortar with a pestle in a little hot alcohol. Again it was passed through muslin cloth. The extraction was repeated once more. The filtrates were pooled and filtered through Whatman No.1 and made up to a known volume with alcohol. The filtrates were stored at 4 C. The residue was preserved for the estimation of starch by (Sadasivam and Manickam, 1992). Aliquots of alcohol extract were evaporated for estimation of total sugar and reducing sugar. For estimation of reducing sugar aliquots samples were made up to one millilitre with distilled water to which one millilitre of alkaline copper reagent freshly prepared was added and kept in a boiling water bath for 20 mn. To each tube after cooling to room temperature, one millilitre of arsenomolybdate reagent was added, immediately mixed thoroughly till effervescence ceased and made up to 20 millilitres. The absorbance was read at 510 nm. For total sugar, the alcohol free samples were hydrolysed with 1 N HCl acid at 100 C for 5 mn along with the alkali, 1 N NaoH using phenolphthalein as an indicator. The sample was reneutralised with 1N HCl acid and made up to known volume. Reducing sugar is expressed in mg/ 100g of the fresh weight. 3.3 OPTIMIZATION OF PROCESSING OF POTATO PRODUCTS Processing improves colour, texture, flavour, acceptability as well as enhances shelf life of the products. Suitability of potato tubers for processing into acceptable product viz., dehydrated chips, fries, ready-to-eat custard and halwa powder, starch powder etc. are required. Processing characteristics of tubers are influenced by many factors. viz., environmental, physical, chemical and post harvest technology. Potato processing helps to utilize the surplus potatoes available and to avoid wastage; it increases the value of raw potato as well as extends the self life Preparation of chips Chips from fresh tubers were prepared as per standard procedure given by CPRI, Shimla (Marwaha et al., 2008). Well cured uniform size tubers of weight 100g-150 g from each variety were fried in 150 ml of groundnut oil during chips preparation. Preliminary trials were conducted for optimization of chips preparation using automatic slicing machine with adjustable blade for slice width (Plate 1). Keeping Kufri Pukhraj as standard, a total of 24 trials with variation in slice thickness (1.8mm and 2.0mm), drying temperature of blanched slices (5mn,7mn and 9mn), frying time of potato slices (3mn and 4mn) and frying temperature (180 C and 185 C) in 150 ml of ground nut oil was carried out to yield potato chips of optimum quality. The most acceptable combination of variables were adopted for preparation of chips and were extended to other varieties. The flow chart for preparation of chips has been presented in Fig Cooking of potatoes by different methods Based on the common methods of cooking, popularity and convenience, pressure cooking and baking methods were employed in the present study. Tubers weighing 100 g g were cooked under pressure cooker as well as microwave Pressure cooking Pressure cooker of aluminium make with capacity of 3 l and pressure 15 lb/inch 2 was used to optimize the process of cooking. The procedure was standardized using Kufri Pukhraj for optimum doneness and known-time and similar was extended to other varieties. The standardized method for pressure cooking of potato tubers has been presented in Fig.3.

26 Plate 1. Automatic slicing machine used for chips preparation Baked potato Keeping Kufri Pukhraj as standard, variation in weight ( g, g, g) and time (3mn, 4mn and 5mn) of baking of potatoes at 100 power density was standardized in microwave oven of KINSTON making. The oven had rated voltage-230 V, input-1250 W, output-800 W and frequency-2450 MHz. The standardized procedure to yield well cooked and highly acceptable baked potato was adopted for rest of the varieties. The process of optimization of baking potatoes has been outlined in Fig SCREENING OF POTATOES FOR PROCESSED PRODUCTS Screening of potato cultivars enable to select the most suitable variety for processing. Potatoes from each variety were screened for peel loss, slice yield, yield of potato chips, surface oil content and colour score. The quantitative parameters were expressed in percentage. For cooked potato flesh loss, doneness, peelability of skin, skin and flesh colour of cooked potato was recorded Potato chips Peel loss The peel loss of raw potato tubers was calculated for 100 g in each variety in triplicate and expressed in percentage (Talburt and Smith, 1975). Initial wt (g 1 ) - final wt potato (g 2 ) Peel loss (%) = X 100 Initial weight (g)

27 Fig.2: Flow chart for chips preparation

28 Fig.3: Flow chart for cooking of potatoes

29 Yield of slices Yield per 100 gram of raw slices were determined. Samples were worked in triplicates. Yield of slices was obtained using the following expression (Nema and Prasad, 2004). Weight of raw potato slices (g) Yield (%) = X Yield of potato chips Wt of raw potato (g) Yield of chips per 100 gram of raw potato was calculated for each variety in triplicates using formula and expressed in per cent (Nema and Prasad, 2004). Weight of fried potato chips (g) Yield (%) = X Surface oil content of chips Wt of fresh potato (g) Surface oil content of the chips was measured in triplicates by conventional method using tissue paper. A single chip was placed between the two folds of tissue paper and pressed with both palms. Weight of tissue paper with and without oil was recorded in mg. The oil content for 100g of chips was calculated. Final weight of tissue paper - initial weight of tissue paper Oil content (%mg)= X Colour score Initial weight of tissue paper Colour scoring of chips was done using colour chart ranging from 1-10 scale. Lesser the score, better is the colour of the chips. Thus score 1 was excellent due to light appealing colour and 10 was grade as highly unacceptable due to dark brown colour. However, up to colour score of 5, the chips were acceptable (Singh et al., 2009) Cooked potato (Baked and pressure cooked) Cooked potatoes including baking by microwave oven and pressure cooking were screened for their suitability Flesh loss The flesh loss of cooked potato was calculated in triplicate and expressed as follows Weight of flesh (g 1 ) Flesh loss (g %) = X Doneness Weight of cooked potato (g 2 ) The doneness of cooked potato was recorded by placing cooked potato in lengthwise direction and pressing it in between the thumb and index finger. Doneness was expressed as well cooked and semi cooked Peelability of skin The ease of hand peeling of skin of cooked potato was recorded as easy to peel or hard to peel.

30 Colour of cooked potato Skin colour viz., brown, brownish yellow, yellowish brown, creamish brown and light brown as well as flesh colour viz., cream, creamish yellow, yellow, white, whitish yellow of cooked potatoes were categorised and recorded. 3.5 ORGANOLEPTIC EVALUATION OF THE PROCESSED PRODUCTS Organoleptic evaluation of processed potato products viz., potato chips (Appendix I), pressure cooked potato (Appendix II) and baked potato (Appendix III) was carried out by 10 trained panellists of Dept. of Food Science and Nutrition using nine point hedonic scale (Appendix I) Total score Mean of the sensory scores given by trained judges for each organoleptic parameter viz., appearance (m 1 ), texture (m 2 ), flavour (m 3 ), taste (m 4 ), overall acceptability (m 5 ) for different processed products i.e. chips, pressure cooked potato and baked potato was calculated. Mean score of all the five organoleptic parameters were summated to obtain total score (M) with maximum score of 45, as mentioned below: Total score (M) = m 1+ m 2+ m 3+ m 4+ m Acceptability Index Acceptability Index (%) for the each processed product was calculated using total scores as given below: Total score Acceptability Index = X 100 Maximum score (45) 3.6 STATISTICAL ANALYSIS The observation recorded were statistically analysed for all the parameters to study the variance between and within the varieties by using CRD (complete randomized design) single factor. The statistically significant differences were analysed using F test. The relation between physical and chemical parameters was verified by correlation using SPSS (Statistical package for social science) software. Ranking of variables was done with Duncan Multiple Range test (DMRT) using M stat software. SEM (Standard error), CD (Critical difference), CV (Coefficient of variance) was assessed using formulas i.e. MSSE/r, 2*SEM*TINV (probability, degree of freedom) and ( (MSSE)/mean)*100 respectively. Mean standard deviation was calculated.

31 4. RESULTS Potato is one of the most important food crops in developed as well as in developing countries. India is amongst the five major potato producing countries in the world. Many potato varieties and hybrid have been released in India, however the demand for processed potato products has led the manufacturer to select the most suitable and round year available potato variety, so that there will be continuous supply of products in the market. The results of the investigation on different potato cultivars (Plate 2a and 2b) assessed for physical, chemical and processing has been presented. 4.1 PHYSICO - CHEMICAL COMPOSITION OF POTATO TUBERS Tuber shape and size are important characteristics that influence peeling and trimming efficiency during processing. Potato tubers that are round in shape have shown to be suitable for crisps preparation for most processors because they easily make required crisp diameter. Physical and chemical composition of potato tubers vary with varieties, area of cultivation, cultural practices, maturity at harvest and storage conditions Physical characteristics of potato tubers The physical parameters of different potato cultivars are presented in Table 1. Tuber mean length varied significantly (p 0.01) between the cultivars ranging from 5.9 cm in J/ to 7.6 cm in Kufri Ashoka. DMRT ranked Variety Kufri Ashoka in first place as it had longest diameter. No significant (p 0.01) difference in length was recorded by Kufri Ashoka compared to control - Kufri Pukhraj, whereas J/ had significantly (p 0.01) shorter length and ranked least. Mean breadth of sample ranged from 4.4 cm to 5.6 cm with shortest in Kufri Pushkar and longest in Atlanta. No significant difference was found between Kufri Pukhraj and other varieties viz., Kufri Chipsona-2, Atlanta, Kufri Khayti, Kufri Jyoti and Kufri Ashoka, whereas rest of the varieties had significantly (p 0.01) lower breadth value. Kufri Ashoka showed largest mass (113g), highest volume (106.9 cc) and longest diameter (5.8 cm) compared to Kufri Pukhraj, while Kufri Pushkar had significantly (p 0.01) smallest mass and lowest volume. Kufri Surya had significantly (p 0.01) shortest diameter (4.5 cm). Highest mean specific gravity was observed in Kufri Pushkar(1.160), Kufri Surya(1.160), Kufri Ashoka (1.16) and Kufri Khayti (1.16) with lowest in Kufri Pukhraj (1.09). Compared to Kufri Pukhraj all varieties had higher specific gravity, however difference was not significant between the varieties. Most of the cultivars had brown skin and cream flesh (Table 2). Atlanta, Kufri Jyoti, Kufri Ashoka and J/ had brownish yellow skin whereas rest showed brown skin. Except for Kufri Pushkar with yellowish cream flesh, rest of the varieties viz., Kufri Bahar, Kufri Ashoka and J/99-242had white flesh. Atlanta, Kufri Jyoti and Kufri Khayti revealed round shape, whereas tuber shapes of Kufri Chipsona-2, Kufri Surya, Kufri Pukhraj, Kufri Pushkar, Kufri Bahar and Kufri Ashoka were oval with J/ variety to be misshaped. Results of the total potato defects of potato cultivars are presented in Table 3. External observation revealed absence of scars in most of the cultivars except for Kufri Pukhraj and J/ Green tint was absent in all the varieties. Skin for most of the cultivars was smooth except in Kufri Chipsona-2, Kufri Surya and Kufri Khayti which had rough skin. Number of mean eye depths ranged from 3.6 to 7.8 with least in Kufri Jyoti and highest in Kufri Bahar followed by Kufri Pushkar. Natural depression was found in Kufri Chipsona-2, Atlanta and Kufri Ashoka. The visualized total potato defects on potato skin was found to be negligible. The internal flesh of all the evaluated potato varieties was devoid of hollow hearts and black spots. Kufri Chipsona -2, Atlanta and Kufri Surya were highly acceptable Chemical composition of potato tubers Mean moisture content of the varieties varied from per cent to per cent with lowest in Atlanta and highest in Kufri Pushkar (Table 4). Kufri Pushkar, Kufri Ashoka, J/99-242, Kufri Bahar and Kufri Jyoti had significantly (p 0.01) higher moisture content compared to control variety, whereas rest of the varieties viz., Kufri Chipsona-2, Atlanta, Kufri Surya and Kufri Khayti had significantly (p 0.01) lower values.

32 Plate 2(a). Different potato varieties

33 Plate 2(b). Different potato varieties

34 Table 1. Physical characteristics of potato varieties Size (cm) Sl.No. Varieties # Length Breadth Weight (g) Volume (ml) Diameter (cm) Specific gravity 1 K.Chipsona ±0.81 d 5.31±0.89 a 90.6±13.54 bcd 84.7±13.26 bcd 5.48±0.23 ab 1.15±0.03 a 2 Atlanta 6.24±0.49 h 5.60±0.42 a 95.7±18.85 bc 90.8±18.47 bc 5.41±0.35 b 1.12±0.03 ab 3 K. Surya 6.79±0.39 f 4.83±0.29 b 77.9±12.57 def 72.9±11.40 de 4.52±0.37 d 1.16±0.03 a 4 K. Pukhraj 7.35±0.88 c 5.44±0.53 a 112.5±14.75 a 98.5±12.86 ab 5.51±0.34 ab 1.09±0.07 b 5 K.Khayti 7.49±0.54 b 5.42±0.39 a 107.3±12.97 ab 100±11.40 a 5.64±0.29 ab 1.16±0.04 a 6 K.Jyoti 6.35±0.63 g 5.48±0.46 a 90.4±18.99 bcd 85.2±17.95 bcd 5.32±0.44 b 1.14±0.04 a 7 K.Pushkar 6.12±0.76 i 4.48±0.16 b 64.10±9.42 f 60.8±8.83 e 4.78±0.27 cd 1.16±0.05 a 8 K.Bahar 7.01±0.99 e 4.84±0.25 b 83.7±14.35 cde 78.6±13.35 cd 5.29±0.33 b 1.15±0.04 a 9 K.Ashoka 7.67±1.11 a 5.41±0.32 a 113.4±27.69 a 106.9±26.39 a 5.81±0.50 a 1.16±0.03 a 10 J/ ±0.52 j 4.75±0.38 b 68.5±17.24 ef 78.6±13.35 cd 4.9±0.42 c 1.15±0.04 a F-value 6.0* 6.6* 8.2* 7.2* 11.4* 2.6* S.Em.± CD(0.01) # Mean of 10 randomly selected potatoes, * Significant at 0.01 level Mean ± S.D., Different superscripts within a column indicate significant differences at 0.05 level by DMRT

35 Table 2. Morphological characteristics of potato varieties Colour Sl. No. Variety # Skin Flesh Shape 1 K.Chipsona-2 Brown Cream Oval 2 Atlanta Brownish yellow Cream Round 3 K. Surya Brown Cream Oval 4 K. Pukhraj Brown Cream Oval 5 K.Khayti Brown Cream Round 6 K.Jyoti Brownish yellow Cream Round 7 K.Pushkar Brown Yellowish cream Oval 8 K.Bahar Brown White Oval 9 K.Ashoka Brownish yellow White Oval 10 J/ Brownish yellow White Misshaped # Mean of 10 randomly selected potatoes.

36 Table 3. Total potato defects (TPOD) of potato varieties Sl. No. Variety # Scars Green tint External (skin) Type of skin No. of eyes Natural depression Hollow heart Internal (flesh) Black spot Acceptability 1 K.Chipsona-2 Absent Absent Rough 3.9 Present Absent Absent Highly acceptable 2 Atlanta Absent Absent Smooth 4.2 Present Absent Absent Highly acceptable 3 K. Surya Absent Absent Rough 3.8 Absent Absent Absent Highly acceptable 4 K. Pukhraj Present Absent Smooth 5.6 Absent Absent Absent Less acceptable 5 K.Khayti Absent Absent Rough 3.9 Absent Absent Absent Acceptable 6 K.Jyoti Absent Absent Smooth 3.6 Absent Absent Absent Acceptable 7 K.Pushkar Present Absent Smooth 6.7 Absent Absent Absent Acceptable 8 K.Bahar Absent Absent Smooth 7.8 Absent Absent Absent Less acceptable 9 K.Ashoka Absent Absent Smooth 5.3 Present Absent Absent Less acceptable 10 J/ Present Absent Smooth 4.2 Absent Absent Absent Less acceptable # Mean of 10 randomly selected potatoes.

37 Atlanta with least moisture ranked first for processing. The highest dry matter content was recorded in Kufri Khayti (20.9%) and least in J/ (15.3%). Compared to check, Kufri Khayti had significantly (p 0.05) higher dry matter closely followed by Atlanta, Kufri Surya and Kufri Chipsona-2. The other varieties had significantly (p 0.01) less dry matter content. Starch content ranged from per cent to per cent, where least was found in J/ and highest in Kufri Khayti. Kufri Khayti had significantly (p 0.05) higher starch content compared to control. Compared to control the difference in moisture content of varieties viz., Kufri Jyoti, Kufri Surya and J/ was found to be non significant (p 0.05). Kufri Pushkar and Kufri Khayti ranked first for moisture, dry matter and starch respectively. Statistically significant (p 0.01) difference was observed between the varieties for all chemical constituents analysed. Sugar content of different potato cultivars are given in Table 5. The reducing sugar content of different cultivars differed significantly (p 0.01), least was observed in variety Kufri Pukhraj (55.13 mg/100g) and highest in Kufri Pushkar (210.3 mg/100g). All the nine varieties had significantly (p 0.05) high level of reducing sugar compared to control (Kufri Pukhraj). With low reducing sugar, Kufri Pukhraj ranked first and thus was suitable for processing. Variety J/ with least total sugars (216 mg/100g) and non reducing sugars (104 mg/100g) ranked first. Except for Kufri Surya, Kufri Chipsona-2, Kufri Surya, Kufri Jyoti and Kufri Ashoka had significantly (p 0.05) high total sugar and non reducing sugar compared to control, whereas rest of the varieties had significantly (p 0.05) less total sugar and non reducing sugar compared to check. Kufri Ashoka (569) mg/100g and Kufri Chipsona-2 (686) mg/100g, Kufri Jyoti 816 (mg/100g) had higher total sugar, whereas Kufri Pukhraj (506 mg/100g) had lower total sugar. Significant (p 0.01) negative relationship was found between weight and reducing sugars (r=-0.66) of raw potatoes (Table 6). Increase in weight of raw potatoes, significantly (p 0.01) correlated (r=0.70) with increase in dry matter however did not influence non reducing sugars, total sugars and moisture content of raw potato. Higher the specific gravity higher was the dry matter (r = 0.70) and starch (r = 0.69) contents of raw potatoes. However non reducing sugars, reducing sugars and total sugars did not vary with variation in specific gravity. Length and breadth of potato did not influence the chemical composition of potato. 4.2 OPTIMIZATION OF PROCESSING OF POTATO PRODUCTS Results of preliminary trials for optimization of chips preparation are recorded in Table 7. The traditional method of chips preparation involved washing potatoes followed by peeling, slicing, blanching, washing blanched slices, drying and frying. Variation in thickness of slice, drying time, frying time and frying temperature was carried to obtain chips of optimum quality. With slice thickness of 1.8 mm, drying time of blanched slices - 5 mn, frying time 3 mn and frying temperature 180 C, the chips were very soggy, translucent, glossy in appearance and accumulated high amount of oil. At 185 C the chips were more soggy with high surface oil content. Variation in frying time (4 mn) at 180 C produced chips that were less soggy, glossy and less surface oil. Similar results were obtained when chips were fried at 185 C. With drying time of blanched -7 mn, frying time -3 mn and frying temperature 180 C, chips were dull in colour, less oily but soggy in texture. Similarly at 185 C the chips were less crispy and dull in colour. Increase in frying time (4 mn) produced chips that were crispy, dull coloured with greasy appearance at both frying temperature 180 C and 185 C respectively. At frying temperature of 180 C and 185 C, drying time -9 mn and frying time -3 mn, the chips had acceptable colour crispy texture. With variation of frying time (4 mn) at 180 C the chips were acceptable with good colour and less greasy. However at 185 C, the chips produced were highly acceptable, crispy, opaque and less greasy compared to others. With increase in slice thickness i.e. 2.0 mm, drying time of blanched slices-5 mn, frying time - 3 mn and frying temperature of 180 C, the chips turned to be very soggy, translucent, glossy appearance and accumulated high amount of surface oil thus rendering the chips highly unacceptable. At frying temperature of 185 C, the chips were still very soggy, glossy in appearance and had high surface oil. However increase in frying time (4 mn) and frying at both 180 C and 185 C, yielded chips that were less soggy, less glossy in appearance with less surface oil. Increase in drying time of blanched slices to 7 mn and frying slices for 3 mn both at 180 C and 185 C, produced chips with less surface oil and less crispy that was dull in appearance.

38 Table 4. Chemical composition (%) of potato varieties Sl. No. Variety # Moisture Dry matter Starch 1 Kufri Chipsona ±0.12 a 20.57±0.06 a 72.30±0.52 c 2 Atlanta 78.87±0.58 a 20.70±0.17 ab 73.32±1.87 d 3 Kufri Surya 79.33±0.12 a 20.67±0.12 ab 62.70±1.04 d 4 Kufri Pukhraj 80.67±1.15 b 19.77±0.32 c 64.96±1.62 d 5 Kufri Khayti 79.00±0.20 a 20.93±0.12 a 85.67±1.57 a 6 Kufri Jyoti 82.00±0.00 c 18.00± 0.00 d 65.98±2.68 d 7 Kufri Pushkar 84.53±0.92 d 15.63±0.25 f 68.37±2.82 c 8 Kufri Bahar 83.93±0.12 d 16.07±0.12 e 71.43±3.44 c 9 Kufri Ashoka 84.33±0.23 d 15.67±0.12 f 65.70±1.56 c 10 J/ ±0.81 d 15.30± 0.10 g 52.55±2.06 e F-value 40* 69* 53* S.Em.± CD(0.01) # Mean of 3 replications, * Significant at 0.01 level, dry weight basis. Mean ± S.D., Different superscripts within a column indicate significant difference at 0.05 level by DMRT.

39 Table 5. Sugar content of potato varieties (mg/100g) Sl. No. Variety # Total sugars Reducing sugars Non reducing sugars 1 K.Chipsona ±0.58 g ±11.55 g ±11.27 g 2 Atlanta ±0.58 d 90.33±10.00 e ±10.50 d 3 K. Surya ±0.64 e 60.73±8.66 b ±8.99 e 4 K. Pukhraj ±0.64 de 55.13±2.89 a ±2.63 e 5 K.Khayti ±1.15 a 75.90±5.77 c ±6.90 b 6 K.Jyoti ±0.64 h ±15.28 f ±15.17 h 7 K.Pushkar ±1.33 c ±16.05 h ±15.43 c 8 K.Bahar ±1.27 b ±5.55 f ±4.49 c 9 K.Ashoka ±2.54 f 87.33±12.73 d ±12.50 f 10 J/ ±0.58 a ±2.42 g ±2.76 a F-value 30* 55* 65* S.Em.± CD(0.01) #Mean of 3 replications, Fresh weight basis,* Significant at 0.01 level Mean ± S.D., Different superscripts within a column indicate significant difference at 0.05 level by DMRT.

40 Table 6. Correlation (r) between physical parameters and chemical composition (%) of fresh potatoes Sl. No. Parameters Specific gravity Weight (g) Length (cm) Breadth (cm) 1 Non reducing sugars (mg) NS NS NS NS 2 Total sugars (mg) NS NS NS NS 3 Reducing sugars (mg) NS ** NS NS 4 Moisture (g) NS NS NS NS 5 Dry matter(g) NS 0.700** NS NS 6 Starch (g) 0.690** ** NS NS ** Significant at 0.01 level,* Significant at 0.05 level NS Not Significant

41 Table 7. Preliminary trials for optimization of chips preparation Sl. No. Thickness (cm) Drying time (mn) Variables Frying time (mn) Frying temperature ( C) Descriptive characteristics Unacceptable Unacceptable Unacceptable Unacceptable Unacceptable Unacceptable Unacceptable Unacceptable Unacceptable Acceptable Acceptable Highly acceptable Unacceptable Unacceptable Unacceptable Unacceptable Unacceptable Unacceptable Unacceptable Unacceptable Unacceptable Acceptable Acceptable Acceptable

42 Chips fried at 180 C as well as 185 C for 4 mn were less crispy, more dull and greasy in appearance. As the drying time of blanched slices increased (9 mn) with frying time -3 mn, chips showed acceptable colour at frying temperature of 180 C and similar results were obtained at frying temperature of 185 C. Increase in drying time of blanched slices to 4 mn yielded chips that had good colour and less greasy at both frying temperatures of 180 C and 185 C. Thus potato slices of 1.8 mm thickness, dried for 9 mn, fried for 4 mn at 185 C produced highly acceptable chips. Results pertaining to optimization of pressure cooking of potatoes are presented in Table 8. Potatoes weighing 101g-120g, cooked for 10 mn at 15 lb/inch² were found to be semi cooked and less hard to peel. However potatoes of same weight were well cooked with easy peelability when pressure cooked for15 mn and at 15 lb/inch². Increasing the cooking time for 20 mn yielded over cooked potatoes. During pressure cooking of potatoes (121g-140g) for 10 mn at 15 lb/inch² produced tubers that were semi cooked. But at 15mn and 20 mn of cooking, potatoes were well cooked and easy to peel. Potatoes (141g-160g) cooked at10 mn and 15 mn were half boiled. But the potatoes of same weight were well cooked at 20 mn of pressure cooking. Thus potatoes weighing, at at 15 lb/inch² for 20 mn was found to be optimum for pressure cooking. Microwave baking of potatoes was optimized and details are presented in Table 9. Potato weighing g was semi cooked in 3 mn, well cooked but mashy texture in 4 minutes and hardened in 5 minutes of baking at 100P. Baking of potato weighing g for 3 minutes produced semi cooked tuber which was hard to peel. As the time of baking increased to 4 mn, tuber was well cooked and had soft texture. However for 5 minutes of baking, tuber produced dry and hard texture. With weight ranging from 141g to 160g and baking time of 3 mn and 4 mn yielded semi cooked baked potato which was hard to peel. However for 5 minutes potato was well cooked with soft texture. Thus baking of tubers weighing 101g-140g at 100 P for 4 mn was found to be optimum for microwave cooking. 4.3 SCREENING OF POTATOES FOR PROCESSED PRODUCTS The quality parameters pertaining to suitability of potatoes for different processed products are presented in Table 10. Significant difference (p 0.01) between the varieties was observed for peel loss with maximum loss by Kufri Chipsona-2 (6.2%), while least loss was observed in Kufri Khayti (2.8%) and thus ranked first. Compared to Kufri Pukhraj, Kufri Chipsona-2 showed significantly (p 0.05) heavy peel loss followed by Kufri Ashoka, J/99-242, Kufri Jyoti, Atlanta, Kufri Bahar, Kufri Pushkar, Kufri Surya and Kufri Khayti. Highest yield of slices (91.9 %) and chips (24.6%) were obtained from Kufri Khayti which was significantly (p 0.05) high compared to Kufri Pukhraj. Least quantity of slices and chips were produced by Kufri Pukhraj (78.3%) and Kufri Ashoka (19.7%) respectively. Kufri Khayti ranked first w.r.t slice yield. Significant difference (p 0.01) among the varieties was observed for yield of chips with maximum yield by Kufri Khayti (24.6%), while least yield was observed in Kufri Ashoka (19.7%) and thus ranked first (Table 11).The present findings for Kufri Pukhraj and Kufri Jyoti w.r.t. chips yield is in corroboration with Marwaha et al. (2008) and Singh et al. (2009) whereas for Kufri Ashoka, Kufri Bahar, Kufri Chipsona-2 and Kufri Jyoti was higher than those reported earlier (Raj and Lal, 2008; Singh et al., 2009; Marwaha et al., 2008). Surface oil and moisture content in chips was highest in Kufri Ashoka with 16.8 mg/100g and 6.5 g (%) respectively. Kufri Khayti had least surface oil content (5.1 mg/100g), whereas Kufri Chipsona-2 had least moisture contents of 3.6 g/100g and thus both ranked best. Compared to Kufri Pukhraj, Kufri Ashoka had significantly (p 0.05) higher amount of surface oil and moisture contents. The colour score of the chips ranged from 2 to 7 with least for Kufri Pukhraj (2) and Kufri Khayti (2) which ranked first followed by Kufri Surya (2.3). Kufri Pushkar obtained significantly (p 0.05) high score (7) compared to control variety and ranked least.

43 Table 8. Preliminary trials for optimization of pressure cooking of potatoes Sl. No. Weight Variables Time Descriptive characteristics (g) (mn) Semi cooked, little hard to peel Well cooked, easy to peel Over cooked, high flesh loss Semi cooked, hard to peel well cooked, easy to peel Well cooked, easy to peel Semi cooked, hard to peel Semi cooked, hard to peel Well cooked, easy to peel Table 9. Preliminary trials for optimization of microwave baking of potatoes Sl. No. Weight (g) Variables Time (mn) Descriptive characteristics Semi cooked Well cooked, soft texture Over cooked, texture became too dry Semi cooked, hard texture in centre Well cooked, soft texture Over cooked, too dry and hard Semi cooked, hard texture Semi cooked, hard texture in centre Well cooked, soft texture

44 Table 10. Quality parameters of raw potatoes from different varieties (g%) Sl. No. Variety # Peel loss Yield of slice 1 K.Chipsona ±0.38 e 86.37±0.85 c 2 Atlanta 5.40±0.12 c 84.00±0.35 d 3 K. Surya 2.90±0.91 a 88.10±0.56 b 4 K. Pukhraj 4.04±0.88 b 78.30±0.56 g 5 K.Khayti 2.84±0.17 a 91.93±0.90 a 6 K.Jyoti 5.57±0.71 cd 83.20±1.15 de 7 K.Pushkar 3.24±0.06 a 86.80±0.35 c 8 K.Bahar 4.27±0.55 b 82.07±0.60 ef 9 K.Ashoka 5.97±0.21 de 82.47±0.47 ef 10 J/ ±0.10 cde 81.57±0.06 f F-value 19* 105* S.Em.± CD(0.01) #Mean of 3 replications Fresh weight basis,* Significant at 0.01 level Mean ± S.D., Different superscript within a column indicate significant difference at 0.05 level by DMRT

45 4.4 ORGANOLEPTIC EVALUATION OF PROCESSED PRODUCTS Sensory quality parameters in the examined crisps (Plate 3a and 3b) from different potato varieties differed significantly (p 0.01) (Table 12). Variety Kufri Khayti scored highest for appearance, flavour, texture and overall acceptability for fried chips. Kufri Jyoti recorded maximum scores for taste. Lowest score for appearance was recorded by Kufri Pushkar. J/ and Kufri Ashoka secured lowest score for flavour, taste, texture and overall acceptability. Flavour, texture and overall acceptability scores for Kufri Khyati were significantly (p 0.05) high compared to the check. Appearance scores for Kufri Khayti did not differ significantly (p 0.05) from that of Kufri Pukhraj, while Kufri Jyoti had significantly (p 0.05) high score for taste compared to Kufri Pukhraj and ranked first. Acceptability indices of potato chips are presented in Table 13. Total score of chips ranged from 38 to 21 with highest in Kufri Khayti and lowest in Kufri Ashoka and corresponding indices ranged from per cent and per cent respectively. Kufri Khayti secured first rank followed by Kufri Surya, Kufri Jyoti, Kufri Chipsona-2, Kufri Pukhraj, Atlanta, Kufri Bahar, J/99-242, Kufri Pushkar and Kufri Ashoka. Quality parameters of pressure cooked potato cultivars are shown in Table 14. Flesh loss of pressure cooked potato was highest in Kufri Surya (7.2%) and least in J/ (9.6%) which ranked first. Compared to control, Kufri Surya had significantly (p 0.05) huge flesh loss while Kufri Bahar, Kufri Khayti and J/ showed significantly (p 0.05) low flesh loss. Except for J/ (brownish yellow), other varieties had brown coloured skin. Majority of the cultivars showed cream colour for flesh closely followed by yellowish cream in Kufri Chipsona- 2 and Kufri Pukhraj, creamish yellow in Atlanta and J/99242, yellow in Kufri Surya and Kufri Khayti, and whitish yellow in Kufri Bahar. All the pressure cooked potatoes were well cooked with easily peelable skin. The sensory profile of pressure cooked potato (Plate 4a and 4b) of different cultivars are shown in Table 15. Appearance of Kufri Chipsona-2 and Kufri Pushkar was best followed by Kufri Jyoti, J/99-242, Kufri Ashoka and Kufri Pukhraj. No significant (p 0.01) difference among the varieties for textural score was observed. The difference between scores for appearance of Kufri Ashoka, J/ and Kufri Pukhraj was not significant (p 0.05). Variety Kufri Jyoti, Kufri Chipsona-2 and Kufri Pushkar found to be best in terms of flavour, taste and overall acceptability. Kufri Jyoti and Kufri Pushkar ranked first with respect to flavour (7.6), taste (7.5) and over all acceptability (7.6). Least ranking was observed w.r.t. flavour (4.3), taste (4.4) and overall acceptability (4.8) for Kufri Khayti. Significant (p 0.01) difference was found between the varieties for all the parameters except for texture. Among pressure cooked potatoes, Kufri Jyoti was ranked first followed by Kufri Pushkar and Kufri Khayti ranked least with scores 37.4, 37, 27 and acceptability indices of 83.1 per cent, 82.2 per cent and 60 per cent respectively (Table 16). Flesh loss of baked potatoes ranged from 3.8% to 12.9% with lowest in Kufri Pukhraj which ranked first (Table 17). Loss of flesh differed significantly (p 0.01) among the cultivars. There was significantly (p 0.05) huge loss of flesh in Kufri Jyoti compared to Kufri Pukhraj. Majority of the baked potatoes including Kufri Chipsona-2, Kufri Khayti, Kufri Bahar and Kufri Ashoka had brown skin. Kufri surya and J/ had brownish yellow skin colour while Kufri Pushkar and Kufri Pukhraj exhibited creamish brown and Atlanta showed yellowish brown colour. Flesh colour of baked potato cultivars viz., Kufri Khayti, Kufri Jyoti, Kufri Pushkar and Kufri Ashoka was yellowish cream whereas Atlanta, Kufri Pukhraj and Kufri Bahar had cream flesh. Kufri Chipsona-2 had yellow flesh colour while Kufri Surya and J/ had white flesh. Except for Kufri Jyoti, skin of all the baked potato varieties was easy to peel. Kufri Surya and Kufri Jyoti were semi cooked, rest of the varieties were well cooked. All the sensory parameters differed significantly (p 0.01) among the varieties, with exception for texture in baked potatoes (Table 18). Highest scores for appearance (7.9), texture (7.6) and overall acceptability (7.4) were given to Kufri Pushkar (Plate 5a and 5b). Least scores for texture were given to J/ (6) and Kufri Bahar while Kufri Surya scored least for over all acceptability. Kufri Jyoti secured the highest score for flavour (7.2) and taste (7.1). Least scores for flavour (4.6) and taste (3.6) were obtained by Kufri Surya.

46 Plate 3(a). Chips from different potato varieties

47 Plate 3(b). Chips from different potato varieties

48 Table 11. Quality parameters of fried potato chips (mg, g %) Sl. No. Variety # Yield of chips (g) Surface oil content (mg) Chip colour score Moisture (g) 1 K.Chipsona ±0.35 cd 8.60±0.81 b 5.33±0.58 d 3.67±0.29 a 2 Atlanta 22.83±0.76 cd 7.80±0.15 b 3.67±0.58 bc 4.50±0.00b d 3 K. Surya 23.4±0.62b cd 12.07±0.65 d 2.33±0.58 a 4.50±0.00b d 4 K. Pukhraj 22.50±0.44 d 12.43±1.10 de 2.00±0.00 a 4.67±0.29 e 5 K.Khayti 24.60±0.8 a 5.13±0.32 a 2.00±0.00 a 4.50±0.00b d 6 K.Jyoti 23.60±0.36 bc 14.17±0.42 f 4.33±0.58 c 4.17±0.29 cd 7 K.Pushkar 22.97±0.25 cd 11.47±0.00 c 7.00±0.00 e 4.17±0.29 cd 8 K.Bahar 24.23±0.58 ab 13.33±0.35 be 4.33±0.58 c 4.33±0.29 de 9 K.Ashoka 19.73±0.50 f 16.80±0.52 g 3.33±0.58 b 6.50±0.50 f 10 J/ ±0.21 e 10.00±0.17 c 5.33±0.58 d 4.00±0.50 b F-value 21* 66* 89* 35* S.Em.± CD(0.01) #Mean of 3 replications Fresh weight basis,* Significant at 0.01 level Mean ± S.D., Different superscripts within a column indicate significant difference at 0.05 level by DMRT.

49 Table 12. Organoleptic profile of potato chips from different varieties Sl. No. Variety # Appearance Texture Flavour Taste Overall acceptability 1 KCchipsona-2 5.4±1.51 cde 6.9±1.29 abcd 6.9±1.20 ab 6.8±1.14 ab 6.1±1.37 bcd 2 Atlanta 6.4±1.71 bc 5.4±1.96 e 6.4±0.97 ab 6.1±0.86 abc 5.9±0.88 cde 3 K. Surya 7.0±1.05 ab 7.5±0.97 ab 7.3±1.16 a 7.2±1.03 a 7.2±1.03 ab 4 K. Pukhraj 7.8±0.79 a 5.8±1.68 de 5.6±1.58 bc 5.5±1.58 c 6.4±1.17 bcd 5 K.Khayti 8.0±0.82 a 7.8±0.92 a 7.4±1.07 a 7.3±0.95 a 7.7±0.82 a 6 K.Jyoti 7.1±0.88 ab 7.2±0.79 abc 7.3±0.95 a 7.3±0.95 a 7.1±0.55 abc 7 K.Pushkar 4.1±2.13 e 6.7±1.64 abcde 4.9±1.80 c 5.3±1.64 c 4.8±1.69 ef 8 K.Bahar 5.9±1.52 bcd 6.1±1.10 cde 6.1±1.37 abc 6.1±1.66 abc 6.0±1.42 bcd 9 K.Ashoka 5.7±1.49 bcd 2.7±1.25 f 4.8±1.40 c 3.9±1.52 d 4.0±1.42 f 10 J/ ±1.89 de 6.2±1.23 bcde 5.6±1.71 bc 5.9±1.37 bc 5.4±1.43 de F-value 7.8* 12.1* 5.3* 6.7* 8.3* S.Em.± CD(0.01) # 9 point Hedonic scale * Significant at 0.01 level, Mean ± S.D., Different superscripts within a column indicate significant difference at 0.05 level by DMRT.

50 Compared to control, Kufri Pushkar obtained significantly (p 0.05) higher score for appearance, texture and overall acceptability. Variety Kufri Bahar had significantly (p 0.05) higher flavour and taste score compared to Kufri Pukhraj. Among the baked potato varieties, highest acceptability index was for Kufri Jyoti and lowest for Kufri Surya (Table 19), whereas rest of the varieties viz., Kufri Pushkar (78.2), Kufri Ashoka (70), Kufri Bahar (70.8), J/ (70.22), Kufri Chipsona-2 (69.7), Atlanta (68), Kufri Pukhraj (62) and Kufri Khayti (64.4) had indices in between to Correlation between physical parameters and quality of processed products showed that as the specific gravity increased, yield of slices (r = 0.68) as well as yield of chips (r = 59) increased which was significant at 0.05 level.however, surface oil content of chips and flesh loss of pressure cooked as well as baked potato was not affected by specific gravity. Length and breadth of potato did not influence yield of slice, yield chips, surface oil content and flesh loss of both pressure cooked and baked potatoes (Table 20). Dry matter content of potatoes showed a positive relation with yield of slices, yield of chips and colour which was (p 0.05) significant (Table 21). Flesh loss of pressure cooked potato did not vary with dry matter content of raw potatoes. Increase in reducing sugars (r = ) darkened the chips colour and did not affect rest of the quality parameters. One of the quality parameters (surface oil content) of processed products were affected by non reducing sugars and total sugars. Increase in moisture content of raw potatoes enhanced oil absorption by chips during frying which was evident in increased surface oil content of chips. Whereas significant (p 0.05) negative correlation was found between surface oil content and starch content of potato tubers. Reducing sugars had significant (p 0.01) negative correlation (r = ) with appearance scores (Table 22).Total sugar and non reducing sugars had no impact on sensory parameters of potato chips. Increase in dry matter content of potatoes increased sensory scores of appearance, texture, flavour and over all acceptability with exception of taste. Starch content showed significant (p 0.05) positive relation (r = 0.67) with texture. Higher the moisture content in raw potatoes, lower were the textural scores and vice versa. Correlation between chemical composition and sensory parameters of pressure cooked potato are presented in Table 23. There was no significant correlation between chemical composition and sensory parameters of pressure cooked potato. The data on correlation revealed that dry matter was positively correlated with flavour (r = 0.68) and taste (r = 0.67) of baked potatoes, whereas other chemical parameters did not influence the sensory profile of baked potatoes (Table 24). Thus, all the potato cultivars were suitable for processing in terms of physical parameters including length, breadth, mass, diameter, volume and specific gravity desirable for processing devoid of scars, green tints, deep eye depths that are oval and round shaped. Variety Kufri Khayti followed by Kufri Pukhraj were found to be most suitable for preparation of chips as it contained optimum dry matter, starch, moisture, total sugar, non reducing sugar and reducing sugar as well as colour score followed by Kufri Pukhraj, Kufri Surya, Kufri Chipsona-2 and Atlanta. Economically, Kufri Khayti, Kufri Surya and Kufri Pukhraj varieties were suitable for processing due to least peel loss and high yield of slice and chips. Varieties Kufri Khayti, Kufri Bahar and J/ were good from health point due to less surface oil. Chips prepared from Kufri Khayti, Kufri Surya, and Kufri Pukhraj had better sensory profile due to appealing colour, appearance, crispiness and taste compared to other varieties. Kufri Pushkar and Kufri jyoti were found to be more suitable for both pressure cooking and baking due to better organoleptic parameters. However due to less flesh loss and doneness, Kufri Khayti and Kufri Bahar were suitable for pressure cooking while Kufri pukhraj and Kufri Surya were suitable for baking.

51 Plate 4(a). Pressure cooked potatoes from different varieties

52 Plate 4(b). Pressure cooked potatoes from different varieties

53 Table 13. Acceptability indices of potato chips Sl. No. Varieties Total scores (Max 45) Acceptability index (%) Rank 1 K.Chipsona IV 2 Atlanta V1 3 K. Surya II 4 K. Pukhraj V 5 K.Khayti I 6 K.Jyoti III 7 K.Pushkar IX 8 K.Bahar VII 9 K.Ashoka X 10 J/ VIII

54 Table 14. Quality parameters of pressure cooked potatoes from different varieties Colour Sl. No. Variety # Flesh loss $ Skin Flesh Doneness Peelability 1 K.Chipsona g Brown Yellowish cream Well cooked Easy to peel 2 Atlanta 2.53 d Brown Creamish yellow Well cooked Easy to peel 3 K. Surya 7.10 h Brown Yellow Well cooked Easy to peel 4 K. Pukhraj 2.10 c Brown Yellowish cream Well cooked Easy to peel 5 K.Khayti 1.60 b Brown Yellow Well cooked Easy to peel 6 K.Jyoti 3.06 ef Brown Cream Well cooked Easy to peel 7 K.Pushkar 3.30 fg Brown Cream Well cooked Easy to peel 8 K.Bahar 1.70 bc Brown Whitish yellow Well cooked Easy to peel 9 K.Ashoka 2.76 de Brown Cream Well cooked Easy to peel 10 J/ a Brownish yellow Creamish yellow Well cooked Easy to peel # Mean of 3 replications, $ Different superscripts within a column indicate significant difference at 0.05 level by DMRT.

55 Table 15. Sensory mean scores of pressure cooked potatoes from different varieties Sl. No. Variety # Appearance Texture Flavour Taste Overall acceptability 1 K.Chipsona-2 7.4±0.97 a 7.4±0.97 a 7.3±0.67 a 7.2±0.79 a 7.4±0.97 a 2 Atlanta 6.8±0.92 a 6.8±0.79 a 7.0±0.82 ab 6.8±1.14 abc 6.8±0.79 ab 3 K. Surya 6.7±1.42 a 6.9±1.45 a 6.5±1.72 ab 6.9±1.73 ab 6.6±1.78 ab 4 K. Pukhraj 7.2±1.40 a 7.0±0.94 a 6.4±1.07 ab 5.8±1.69 bc 6.5±1.08 ab 5 K.Khayti 6.8±1.48 a 6.7±1.42 a 4.3±1.83 c 4.4±2.22 d 4.8±2.04 c 6 K.Jyoti 7.3±1.06 a 7.4±0.97 a 7.6±0.70 a 7.5±0.85 a 7.6±0.70 a 7 K.Pushkar 7.4±1.26 a 7.3±0.95 a 7.2±1.03 ab 7.5±0.97 a 7.6±0.84 a 8 K.Bahar 5.0±1.41 b 6.7±1.42 a 6.0±1.56 b 5.5±1.43 cd 5.9±1.45 b 9 K.Ashoka 7.2±1.14 a 7.3±0.95 a 6.7±1.06 ab 6.4±1.08 abc 7.1±0.74 a 10 J/ ±1.03 a 7.3±0.67 a 7.0±0.67 ab 6.8±1.14 abc 7.0±0.47 ab F-value 3.4* NS 6.2* 5.1* 5.2* S.Em.± CD(0.01) # 9 Point Hedonic Scale, NS= not significant, * Significant at 0.01 level Mean ± S.D., Different superscripts within a column indicate significant difference at 0.05 level by DMRT.

56 Plate 5(a). Microwave baked potatoes from different varieties

57 Plate 5(b). Microwave baked potatoes from different varieties