MASTER OF SCIENCE IN FOOD SCIENCE & TECHNOLOGY

Transcription

1 STUDIES ON THE USE OF ANTIOXIDANTS AND PRESERVATIVE FOR EXTENDING THE SHELF LIFE OF PEDA By Ramesh Yadav (2003FS113M) Dissertation submitted to the Chaudhary Charan Singh Haryana Agricultural University, Hisar for the partial fulfillment of the requirement for the degree of MASTER OF SCIENCE IN FOOD SCIENCE & TECHNOLOGY CENTRE OF FOOD SCIENCE AND TECHNOLOGY Chaudhary Charan Singh Haryana Agricultural University Hisar

2 KEYWORDS Peda, Storage studies, Antioxidants, Tocopherol acetate, Sodium ascorbate, Preservative, Potassium sorbate, Free fat, Free fatty acid, TBA, NPN, SPC, Sensory evaluation, LDPE.

3 DEDICATED TO MY PARENTS

4 ACKNOWLEDGEMENT Words are inadequate to express my indebtedness for my major advisor Dr.B.S.Beniwal, MDO- cum- Dairy Manager, Department of Animal Products and Technology. His affectionate encouragement, moral support, unending and unlimited interest in this study has made the completion of this work possible. His ever willingness to help and co-operate has set an example for me to follow. I wish to express my gratitude to the members of my advisory committee, Dr. Rajendra Singh, Centre of Food Science and Technology, Dr. M.K. Garg, college of Agriculture Engineering, & Dr. Amar Nath Gupta, College of Veterinary Sciences. for their valuable suggestion and critical evaluation of manuscript. Special thanks are to my friends Mr. Anil Boora, Naresh, Munish, Narender, Tarsem, Pradeep and all my other class mates for their help and friendship which have made my stay in the university a memorable experience. Last but not least, I acknowledged my natural gratefulness to my beloved parents and all my family members who have been inspiring me to see my work fruitfully completed. I also acknowledge my brother Krishan Yadav who helped me in typing this manuscript.

5 Ramesh Yadav CERTIFICATE I This is certify that this dissertation entitled Studies on the use of antioxidants and preservative for extending the shelf-life of peda submitted for the degree of Master of Science, in the subject of Food Science and Technology to the Chaudhary Charan Singh, Haryana Agricultural University, Hisar, is a bonafide research work carried out by Ramesh Yadav under my guidance and supervision and that no part of this report has been submitted for any other degree. The assistance and help received during the course of investigation have been fully acknowledged. Dr. B.S. Beniwal Technology Deptt. of Animal Products

6 Hisar CCS HAU, CERTIFICATE-II This is certify that this dissertation entitled Studies on the use of antioxidants and preservative for extending the shelf-life of peda submitted by Ramesh Yadav to the Chaudhary Charan Singh, Haryana Agricultural University, Hisar, in partial fulfillment of the requirement for the degree in Master of Science in the subject of Food Science of Technology, has been approved by the student s Advisory Committee after an oral examination. HEAD OF THE DEPARTMENT MAJOR ADVISOR

7 DEAN, POST-GRADUATE STUDIES CONTENTS Sr. No. Chapter Pages 1. Introduction Review of Literature Materials and Methods Result & Discussion Summary & Conclusion Bibliography i-iv Appendix I

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9 CHAPTER I INTRODUCTION Milk is an important agricultural product of India. Presently India is the largest producer of milk. It is estimated that India produces about 88 million ton of milk per year. Milk is an essential component of our diet and certain minimum daily consumption levels have been recommended by various agencies. To add variety to our food and to carry forward the constituents of highly perishable milk, various products are prepared from it. About seven per cent of total milk produced in India is converted into Khoa (Rajorhia and Srinivasan, 1979) and using Khoa as base material, Peda is produced and the quantity of Peda produced in India exceeds any other indigenous milk based sweet. (Kumar et al., 1997) Peda is a popular and nutritious milk sweet. It is a rich source of energy and protein. This traditional sweet is used in various ceremonies and festivals. It is prepared from Khoa, obtaining by scalding fresh milk in an open pan. Usually Peda is prepared by heating Khoa in a pan until the moisture content is reduced between %, adding sugar in requisite amount followed by forming the sweetened dough into flat, and circular pieces. The manufacture of

10 Peda is mostly restricted to halwais, consequently alarming variations are encountered in the composition of Peda. (Rajorhia and Srinivasan 1979) Peda in comparison with Burfi is granular and harder in texture and having a longer keeping quality. Numerous varieties of Peda are manufactured, the method of which vary from region to region depending on the consumer requirement. Regional preferences for quality determine the method of preparation as a result of which the sensory and chemical attributes vary considerably. Some prefer white color of Peda and other may ask for yellowish color. Highly cooked to burnt flavor remains the attribute of choice in certain sections. The preference for texture also varies from soft to grittiness. The choice of size and shape is of minor consideration. (Reddy and Rajorhia, 1992). Peda by virtue of its lower moisture and higher sugar contents, is expected to be less susceptible to microbial spoilage than Khoa. However Peda is most susceptible to microbial spoilage due to unhygienic conditions adopted during manufacturing and handling and its surface contaminations. The Shelf Life of Peda at room temperature is seldom more than 48 hours. Peda is usually prepared and sold in sweetmeat shops and small restaurants country wide. The product is displayed in glass shelves, often without any packaging for few days before being sold out. Prolonged storage under ambient conditions adversely

11 affects the consumer acceptability due to textural changes caused by desiccation or alteration of the flavor profile. Also the possibility of mold growth should not be overlooked. Various attempts have been made to enhance the Shelf Life of Peda using Modified Atmosphere Packaging (MAP) and vacuum packaging coupled with low temperature storage. (Khader and Patel, 1983, Birader et al. 1985). But as a result of vacuum packaging, crushing/squeezing of Peda takes place making its appearance far less appealing. Peda stored at refrigerated temperature loses its body and texture and mouthfeel. Breakdown of fat during storage is responsible for the rancid odor of Peda and use of antioxidants like Vit.E and Vit.C may prevent it. Further they may add to the nutritional value of Peda. Improvement in the Shelf Life of milk product Peda, will enhance its marketability. Thereby it will improve the salability of farmer s milk. The present study was undertaken with the following objectives: 1. To study the effect of antioxidants and preservative on Shelf Life of Peda. 2. To study chemical and bacteriological changes during storage of Peda.

12 CHAPTER II REVIEW OF LITERATURE The published information available on peda is quite scanty and hence not much literature could be cited on the manufacturing process, composition, sensory characteristics and biochemical changes in peda on its storage. Therefore some relevant literature on indigenous milk products such as khoa, burfi and kalakand, which are similar in nature and characteristics, have also been reviewed. The relevant literature has been presented under the following heads and subheads: 2.1 TECHNOLOGY OF PEDA 2.2 COMPOTION OF PEDA 2.3 QUALITY OF PEDA Chemical quality Microbiological quality 2.4 STORAGE STUDIES 2.1 TECHNOLOGY OF PEDA Patel and De (1977) developed a method for production of dried khoa suitable for use in the preparation of acceptable quality peda, Raw buffaloes' milk was standardized to 5% fat, and homogenized and heated to the

13 khoa-concentrate stage (i.e. dehydration was stopped as soon as complete heat coagulation of milk proteins had occurred); water was then added to give 16-18% TS, and the mixture was gradually heated to 600C, stirred well and passed through a micropulverizer to obtain a smooth slurry which was roller-dried under standard conditions of continuous gravity feeding. Mean chemical composition of the dried khoa was 33.8% fat, 27.2% protein, 30.6% lactose, 5.3% ash and 3.1% moisture. Mean storage life was 90 days when air-packaged and stored at room temp. (16-300C), and 105 and 60 days when N 2 -packaged and stored at room temperature and 370C, respectively. Patel and Gandhi (1980) described the process of manufacturing peda converting 600 litres of buffalo milk into 168 kg peda in an eight hr. shift by developing a set of six crude oil combustion furnaces. About 5 litres of milk was taken per batch. As soon as milk came to first boil, about 450 gram of sugar was added and the stirring and scraping continued until a pasty consistency was obtained. The paste was spread on the walls of the pan for cooling. The product was removed to a tray and molded into desired shapes. The final product contained about per cent moisture. Similar

14 approach in peda making was adopted at the rural milk processing centers in Kutch district run by the Gujrat State Rural Development Corporation. Six litre of milk was heated in an open iron vessel on a diesel furnace and 400 gram of sugar added at the last stage of khoa making. After cooling, the product was rolled and shaped in circular balls of about 25 grams each, measuring 4 cm diameter and 1.5 cm height. Thompkinson and De (1981) gave the technology of peda making from dried khoa. Peda was prepared from fresh as well as stored cow and buffalo khoa powder. Peda made from cow khoa powder was chalky and sticky. Addition of chocolate improved the taste. Peda made from buffalo khoa powder had slight khoa like flavour and smooth body. Acceptable quality of peda could be made using buffalo khoa powder stored up to 105 days at room temperature. Khoa can be stored in dried form for preparation of acceptable quality of peda. Sachdeva and Rajorhia (1982) reported that buffalo s milk with 6 percent fat after conversion into khoa added with 25 to 30 percent sugar while still hot, following whipping with a wooden ladle gave a highly acceptable product (burfi). Addition of 30 to 35 percent sugar in khoa manufactured from cow s milk with 4.5 percent fat was recommended,

15 although the resulting burfi was sticky and gummy. A very few studies have been made with regard to the stage of adding sugar to the base product and to determine the extent of final heating to be accomplished. Sachdeva and Rajorhia (1982) studied the stages of adding sugars for burfi making and found addition of sugar in khoa while it was still hot, as the most appropriate stage. Patel (1986) reported that a crude oil cum-compressed air combustion furnace had been developed by sweet merchant of Rajkot. A quantity of 5 litres of chilled buffalo raw milk (6.0% fat and 9.0% SNF) was being poured into karahi, for desiccation of milk, which was then placed on a burning furnace. Stirring was done manually. When milk came to first boil, a quantity of 450 gms sugar was added. Stirring continued until desired consistency was obtained. This was achieved after about 15 to 18 minutes when the moisture content of the desiccated mass was reduced to about 15 per cent, slight grain formation was noticed at this stage. Punjrath et al. (1990) developed equipment for manufacturing khoa as a continuous process. The equipment reached steady state in 8-12 min and quality of khoa obtained remained unchanged over the periods tested (6-14 h). The equipment comprised a balance tank, a positive

16 displacement pump and an inclined scraped surface heat exchanger of special design. High quality khoa could be manufactured controlling various parameters such as TS in the feed, temp. of feed, ph/acidity of the feed, rotor speed and inclination. Feed with TS of 41-55% and feed temp. of C and steam pressures between 1 and 2 kg/cm 2 were investigated for different qualities of khoa. The equipment was stable, could be cleaned in-place and produced khoa at a rate of kg/h starting with 40-45% TS conc. milk. Product losses were negligible. Rajorhia et al. (1991) compared the performances of 4 mechanized systems of khoa making, i.e., inclined scraped surface heat exchanger (ISSHE), conical vat, contherm-convap heat exchanger and roller drier. Units were run under standardized conditions and the product obtained after different intervals was analyzed for chemical composition, sensory quality and rheological properties. Pertinent operational features were also critically observed. Sensory characteristics of khoa prepared by ISSHE were similar to those of the traditional product and chemical composition and rheological properties of khoa maintained uniformity during continuous system operation for about 10 h. Quality of khoa prepared by the other 3 systems was inconsistent in composition, texture

17 and colour during operation and sensory quality was inferior as compared with traditional khoa. ISSHE was compact and simple and suitable for continuous manufacture of greater than 300 kg of khoa in 1 shift of 8 h. Christie and Shah (1992) outlined and represented diagrammatically the salient constructional and other features of a 3-stage machine for manufacture of khoa. The 1st stage raises the milk solids level from 15 to 25%, the 2nd stage from 25 to 50% and the 3rd stage from 50 to 70%. The capacity was 50 kg of milk/h. Sensorily, the khoa prepared was as good as manually prepared khoa, and the flavour was slightly better than that of khoa prepared in a stainless steel kettle. Benerjee (1997) has mentioned a process for industrial method of peda manufacturing followed by Sugam dairy Baroda. Milk was converted into khoa having 72% total solids by using continuous khoa making machine. Khoa was heated to 60 C and then sugar was added (30% of khoa). Flavour and other ingredients were mixed with khoa in a planetary mixer. Mixed peda mass was stored in deep freeze for 10 hrs. Peda mass temperature was brought down to 5 C and then fed to peda shaping machine and was then packed and stored preferably in

18 refrigerated conditions. 2.2 Composition of peda A number of workers have studied the composition of peda marketed in different parts of the country and reported a wide variation in the same. Ghodekar et al. (1974) reported market peda having (per cent) fat with an average of 9.70, protein with an average of 9.10; lactose with an average of 9.4; ash with an average of 2.0; sucrose with an average of 55.3 and moisture with an average of Sharma and Zariwala (1978) reported market peda having (per cent) fat ; protein ; lactose ; sucrose ; moisture Patel and Gandhi (1980) reported factory peda possessing composition (per cent) fat 20.0, protein 19.5, lactose 16.31,sucrose 31.8 and moisture Miyani et al (1982) reported that peda prepared from cow and pooled buffalo milk, adjusted to different levels of fat viz. 3.0, 4.5 and 6.0 per cent contained 17.36, and of fat and 15.77, and per cent

19 of moisture. Garg and Mandokhot (1987) reported market peda having moisture per cent 13.75; lipid per cent 23.52; protein per cent 17.43; sugar per cent 29.0 and ph Patel (1986) reported that Gopal Peda possessed composition (per cent) moisture 13.5; fat 20; protein 19.5; acidity 0.18 (per cent L.A); lactose 16.3 and sucrose Rajorhia and Sen (1987) reported wide variation in composition of peda as moisture per cent ; fat per cent ; protein per cent ; sucrose per cent ; lactose per cent and ash per cent Reddy and Rajorhia (1992) reviewed the present status of peda technology and reported a wide variation in the chemical composition of peda. The sucrose content in peda varies from 31.8 to 61.3 per cent, fat between 3.3 and 25 per cent, protein from 1.4 to 19.5 per cent and moisture between 4.2 to 18.2 per cent, lactose content between 4.0 to 18.6 per cent and ash content between 1.4 to 3.4 per cent. The quality of khoa, quantity of sugar added, the extent to which the mixture is heated and the storage conditions influence the composition of peda. 2.3 QUALITY OF PEDA

20 2.3.1 Chemical quality Ghodeker et al. (1974) tested a total of 245 samples of khoa, burfi and pera chemically, microbiologically and organoleptically. Chemical composition varied considerably, with moisture % ranging from to in khoa, from 5.4 to 18.4 in burfi, and from 6.8 to 10.7 in pera. Khoa contained on average 27% fat, 19% protein, 25% lactose and no sucrose; burfi contained an average 9% fat, 15% protein, 8% lactose and 52% sucrose; and pera contained an average of 8% fat, 9% protein, 9% lactose and 55% sucrose. No correlation was found between organoleptic grading and bacteriological quality of the samples.. Ghodekar et al. (1980) reported the titrable acidity in peda samples stored at 5-7, 22 and 37 C increased by , and per cent lactic acid on 30, 21 and 14 days of storage, respectively. Miyani et al. (1982) reported that the acidity and the acid degree value remain almost constant up to 7 days and then showed an increasing trend. This was true for both cows and buffalo milk peda. Bhatele (1983) reported the titrable acidity (per cent) in burfi samples 0.46 on 0 day and 0.62 on 5th day in control samples at 30 C whereas

21 0.77 per cent in potassium sorbate treated (0.2%) samples on 50th day at 30 C and 0.79 and 0.60 per cent after 80 days in control and preservative treated samples stored at 7 C, respectively. Vijay Kader and Kalpana (1983) studied the effect of polyethylene on peroxide value during storage of peda. It was reported that peroxide value was 0.51 on 0 day and 0.74, 0.94 and 0.94 on 14th day in peda packed in low, medium and high density polyethylene, respectively. The FFA was 0.47 on 0 day and 0.64, 0.55 and 0.55 on 14th day in three densities of polyethylene packed samples, respectively. Birader et al. (1985) studied the peroxide value and free fatty acids of peda for control and LDPE packed samples recorded at 4 day intervals of over the two weeks storage period. The peroxide value in freshly prepared peda was 1.40 that increased consistently on storage and reached a maximum (4.0) on the 8th day and remained constant at that value up to the 12th day of storage. Packaging has no influence on peroxide value over the entire storage period. The FFA value for fresh peda was that remained constant in LDPE 350 packed samples and only slight increase was observed in the control and in LDPE 300

22 packaged samples up to 8 days and only slight increase was observed in the control (0.068) and LDPE 100 (0.062) packed samples. Beyond this, FFA increased in all the treatments. There was an identical increase in the control and the samples in LDPE 100 while that in LDPE 300 showed only half of that increase. Kumar et al. (1997) reported that change in titratable acidity and ph during storage of peda were very small for all the samples, which remained organoleptically acceptable. The rate of increase of acidity was higher at 37 C than at 20 C. This increase in the lactic acid could not be attributed to the production of lactic acid by microorganisms. The initial value of FFA (0.058) to increased after fifteen days of storage in modified atmospheric packaging at 37 C and at ambient temperature was faster than oxygen scavenger (0.072) packaging in the same corresponding period. Though the rate of increase in FFAs was higher at 37 C, the total increase after two months of storage was only 0.03 per cent. The increase in peroxide value (1.10) in fresh sample was faster at 37 C than at ambient or at 20 C in the same corresponding period. There was no detectable off-flavour in the peda samples till

23 peroxide value reached up to Microbiological quality Sharma et al. (1972) reported that average bacterial counts/g in 220 samples of khoa obtained from the Udaipur city market was: standard plate count, 9.5 million; coliform count, 8700; and enterococcus count, Further tests on 25 representative samples showed an average staphylococcus count of 1.5 million/g. Average counts/ml in 55 samples of raw milk used for khoa production were: standard plate count, 4.8 million; coliform count, ; enterococcus count, ; and staphylococcus count, Standards suggested for satisfactory grade market khoa are: standard plate count, less than 10 million/g; coliform count, less than 5000/g; and enterococcus count, less than /g. Ghodekar et al. (1974) graded 245 samples of khoa, burfi and peda as good, fair and poor. Highest bacterial and fungal counts were noted in khoa as compared to burfi and peda. The SPC of good quality burfi had a maximum count of 8 x 103 and minimum of 2 x 103 with an average of 5 x 103 per gm, whereas in good quality of khoa it ranged from 0.7 x 103 to 30

24 x 103 with a mean value of 5 x 103.The fair quality of burfi showed a maximum of 30 x 103 and a minimum of 3 x 103 with an average of 12.3 x 103 per gm whereas in fair quality khoa it ranged from 45 x 103 to 30 x 104 with an average of 44 x 103 /gm and in poor quality khoa from 150 x 104 to 150 x 106 with an average of 11 x 106 /gm, respectively. Kamat and Sulebele (1974) examined the samples of peda for different counts and showed the presence of mesophilic bacteria being largest in numbers followed by psychrophilic and thermophilic counts. Coliforms surprisingly could not be detected in any of the samples. Staphylococci were detected in 14 out of 16 samples of which four were coagulase positive and 64.3 per cent of the strains isolated haemolysed human red blood cells Singh et al.(1975) reported that average count of standard plate, coliform, staphylococcus, and yeast and mould were 4,500,000, 189,000, 620,000,450 and 610 per gm in peda samples. Ghodeker et al. (1980) observed that 75 khoa, 60 burfi and 50 pera samples respectively, from local halwai shops, had initial counts of 6000, 5000 and 5500 total bacteria/g, 20, 40 and 40 yeasts/g and 10, 20 and 30

25 moulds/g, and 0.21, 0.17 and 0.15% titratable acidity. When stored at various temp., khoa samples became sour after 2 days at 30 0 and 37 0 C, 3 days at 22 0 C, or 7 days at C; burfi and pera samples became sour after 14 days at 30 0 and 37 0 C, 21 days at 22 0 C, or 30 days at C. Increase in acidity resulting from growth of acid-producing bacteria provided a favourable environment for growth of yeasts and moulds. Saccharomyces, Candida, Rhodotorula and Torulopsis spp. were the predominant yeast isolates whilst the predominant moulds were Penicillium, Aspergillus and Geotrichum spp. Presence of moulds was indicative of unhygienic conditions during manufacture and storage. Kumar and Srinivasan (1984) reported that samples of cows' milk khoa, buffaloes' milk khoa and commercial khoa, respectively, had the following mean microbial counts/g: standard plate count, 4400, 5800 and ; acid-producers, 2200, 3200 and 2500; proteolytic organisms, 1500, 2200 and 2500; chromogenic organisms, 1200, 1500 and 2400; lipolytic organisms, 250, 540 and 430; aerobic spore formers, 71, 77 and 31; and yeasts/moulds, 7.5, 10 and 38. Kahlon and Grover (1984) collected 27 khoa, 30 paneer, 31 kulfi, 20 ice

26 cream and 28 dahi samples from various outlets (halwais, vendors, hotels etc.) in Ludhiana. Mean total bacterial count/g, mean staphylococcal count/g, % of samples containing staphylococci, and % with coagulase negative and thermonuclease-positive staphylococci, respectively, were: khoa, 2.3 million, , 85.2 and 30.43; paneer, , , 80.0 and 25; kulfi, , , 87.1 and 48.14; ice cream, , 7000, 65 and 23.07; and dahi, , 1400, 21.4 and It is concluded that standards of hygiene in the manufacture of milk products need to be improved through education of both the rural and urban population. Garg and Mandokhot (1984) reported that 28 burfi and 38 pera samples (sweetmeats made from khoa and sugar), from various manufacturers and shops in Hissar and Hansi, had standard plate counts ranging from 530 to /g and from 1100 to /g, respectively, 11 and 15 samples contained coliforms (determined on eosin/methylene blue agar), 0 and 1 sample contained Escherichia coli, and 5 and 19 contained faecal streptococci. Composition of the microflora of individual samples varied considerably, but the mean total flora of burfi and pera samples, respectively, included: Bacillus spp., 41.2 and 22.3%; Staphylococcus spp.,

27 31.8 and 32.8%; Micrococcus spp., 23.5 and 27.7%; unidentified Gram-positive cocci, 0.1 and 11.7%; faecal streptococci, 0.8 and 0.7%; and total Gram-positive organisms, 98.7 and 98.9%. Few yeasts/moulds were found. Mean chemical composition of 16 burfi and 16 pera samples, respectively, was and 14.99% moisture, and 22.06% lipid and and 13.77% protein; ph range was and , respectively. Kumar and Sinha (1989) carried out a study on the incidence of coliform bacteria (`total' and `faecal') in paneer, gulabjamun and khoa (31, 19 and 20 samples, resp.) obtained from the experimental dairy of the National Dairy Research Institute (Karnal, India), and from local markets in India. For paneer, gulabjamun and khoa, respectively, 84, 74 and 67% of samples showed unsatisfactory levels of coliforms. Values for total and faecal coliforms were (/g): paneer, 7.3 to greater than and 0 to greater than ; gulabjamun, and 0-100; and khoa, and 0-750, respectively. Sohal et al. (1993) investigated the survival of Escherichia coli and Staphylococcus aureus during production of khoa. Heat processing of milk containing from 3.6 to 6.5% fat at either 63 or 730C eliminated all

28 E. coli. Under similar processing conditions, S. aureus was recovered, but only when heated in milk at 63 0 C containing 7.5% fat. Potassium sorbate (3000 ppm) appeared more effective in inhibiting growth of selected yeast and fungi in khoa at 7oC, compared to ascorbic acid (3000 ppm). Reduction of E. coli or S. aureus in khoa during prolonged storage at 6-70C was less than 1 log cycle, regardless of a w or preservative type. Survival of S. aureus in khoa appeared to be enhanced with a decrease in aw. The potential for pathogens to survive in khoa during processing should be taken into consideration when formulating heating protocols. 2.4 STORAGE STUDIES Jha et al. (1977) reported that by the addition of potassium sorbate in khoa 0.2 to 0.3 percent, the keeping quality increased from 4 to 12 days at 300C. Ghodekar et al. (1978) reported that addition of 0.20% potassium sorbate to hot khoa increased shelf life at 7 0 C from 6 to 14 days, at 22 0 C from 2 to 7 days, and at 37 0 C from 2 to 4 days % potassium sorbate was less effective. Impregnation of khoa wrapping paper with 30%

29 potassium sorbate solution doubled the shelf life at 70C, but had less effect on keeping quality at C. According to CFTRI Annual Report ( ) addition of sorbic acid to burfi helped in controlling the visible fungal growth on burfi pieces during open storage even up to 90 days. Bhatele (1983) reported that there was no change in the shelf life of burfi by the addition of 0.3 per cent of potassium sorbate on the basis of sensory evaluation. Both control and the potassium sorbate treated samples were unacceptable after 50 days and 80 days at 30 C and 7 C respectively. Reddy et al. (1985) studied the extension of shelf life of burfi and reported that 50 per cent replacement of cane sugar with corn syrup (42 DE) has shown desirable results to extend the shelf life. He also reported that it also reduces the water activity, thereby exerting an inhibitory influence on the growth of bacteria. An equilibrium relative humidity (ERH) increased the mould growth and the lower impaired the texture of burfi making the product unfit for consumption

30 Suresh and Jha (1994) reported that the addition of potassium 0.2 and 0.25 per cent in kalakand increased the shelf life of the product from 3 to 24 days at 30 C. Kumar et al. (1997) packaged peda in multilayer transparent laminate under Modified Atmospheric packaging (MAP) (N 2 : CO 2 : 80:20) and also under normal atmospheric environment with oxygen scavenger. Samples with MAP showed shelf life of 15 days both at 37 C as well as at ambient temperature, and 30 days at 20 C storage. Packaging of samples with oxygen scavenger extended the shelf life up to 2 months at 37 C, 5 months at ambient temperatures and 6 months at 20 C. Champak (1998) studied the extension of shelf life of burfi using various techniques and reported that the shelf life of burfi at 30 C in parchment paper is about 10 days. Packaging of burfi in pre-sterilized (0.50 H2O2) cryovac pouched increased the shelf life up to 30 days. Packaging of burfi into polystyrene tub and vacuum packaging increased the shelf life to more than 60 days.

31 CHAPTER-III MATERIAL AND METHODS The materials and methods adopted in the present study are discussed under the following heads and sub heads: 3.1 MATERIALS Procurement of Milk Procurement of Tocopherol Acetate

32 3.1.3 Procurement of Sodium Ascorbate Procurement of LDPE Bags Equipments 3.2 METHODS Standardization of Milk Preparation of Peda Antioxidants and Preservative used Chemical analysis of Peda Moisture Fat Protein Lactose Ash Microbial Analysis (SPC) Storage Studies Free Fat Free Fatty acids Thiobarbituric Acid Value Peroxide Value

33 Non Protein Nitrogen Sensory Evaluation Statistical Analysis 3.1 MATERIALS Procurement of Milk The buffalo milk was procured from the Experimental Dairy Plant of APT department, CCS HAU, Hisar Procurement of Tocopherol Acetate Tocopherol Acetate was procured from Himedia Laboratories Mumbai (Bombay) , India Procurement of Sodium Ascorbate Sodium Ascorbate was procured from Himedia Laboratories Mumbai (Bombay) India Procurement of potassium sorbate Potassium sorbate was procured from Himedia Laboratories Mumbai (Bombay) India Procurement of LDPE Bags

34 LDPE bags (50-55 micron) were used which were purchased from the Department of Animal Products Technology CCS HAU, Hisar Equipments Khoa Making Machine A gas operated khoa making machine with 30 ltr. capacity fabricated by SOLAR ARKS Pvt. Ltd., Kohlapur with 105 ltr. Container and S.S. side cover, was used for the preparation of khoa Cream Separator Luxmi cream separator manufactured by Chaddha Industries, New Delhi, India was used for separation of cream. 3.2 METHODS Standardization of Milk The buffalo milk was standardized w.r.t. fat at 6 % and. the excess fat of buffalo milk was removed by using cream separator ( ) Preparation of Peda Khoa was prepared in the above mentioned semi-automatic khoa making machine ( ). Milk in the khoa making machine was heated by LP Gas. After making khoa, sugar was added to khoa at

35 the rate of 7% of milk weight basis. Then the balls were made of about 30 gm each Antioxidants used Preliminary trials were conducted using three levels of Tocopherol acetate (8, 12 and 16 ppm) and Sodium ascorbate (400, 600 and 800 ppm. The best concentration for further studies was selected on the basis of sensory evaluation Chemical Analysis of Peda Moisture The moisture of samples was determined by Gravimetric method as described in AOAC (1995). About 2 gm of the sample was weighed accurately into a dish previously dried and weighed. The dish containing the material was heated in the electric oven maintained at 102±1oC for about 2 hours.it was then taken out and cooled in a desiccator and weighed. The process of drying, cooling and weighing was repeated at 30 minute interval for three or four times till constant weight was attained. The moisture percentage was calculated as follows; Moisture per cent = (W1-W2) 100

36 W1-W Where W1 = Weight in g of the dish with the sample before drying W2 = Weight in g of the dish with the sample after drying W = Weight in g of the empty dish Fat Fat in sample was determined by Mojonnier method (IS : ). About 5 g of sample was accurately weighed into mojonnier tube. Then 10 ml of concentrated hydrochloric acid was added and heated till the sample was completely solubilised. Then 10 ml of absolute ethyl alcohol was transferred to the mojonnier tube. Diethyl ether (25 ml) was added and the mojonnier tube was shaken vigorously for one minute. 25 ml of petroleum ether (40-60oC) was added with repeated vigorous shaking. The mojonnier tube was placed undisturbed for some time till the ethereal layer separated out. The ethereal layer was decanted into a pre weighed dish. The extraction of aqueous solution was repeated twice using 15 ml each of diethyl ether and petroleum ether. The solvent in the dish was dried on steam bath and the residual fat was further dried in the oven at 100±1 o C

37 for one hour followed by cooling in a desiccator and then weighed. Fat percentage was calculated as follows: Fat percentage = Weight of fat x 100 Weight of sample taken Protein Protein estimation was carried out as described in (AOAC, 1995). About 2 g of the sample was weighed accurately and transferred into a Kjeldhal flask. To this a pinch of digestion mixture and 20 ml of conc. sulphuric acid was added. Placed the flask on Kjeldhal apparatus in an inclined position till the mixture was clear. Transferred the content quantitatively, using distilled water to the volumetric flask and diluted to 100 ml volume. The digested material (10 ml) was steam distilled after addition of 20 ml 40% NaOH solution, into 10 ml Boric acid (2%) using mixed indicator (Bromocresol green + Methyl red). The borate ammonia was titrated with 0.01 N H 2 SO 4. A blank determination was also carried out simultaneously and total nitrogen was calculated as: Nitrogen % = (V-B) x 100 x x W

38 Protein % = N % x 6.25 Where : V = Volume of 0.01 N H2SO4 used for sample B = Volume of 0.01 N H2SO4 used for blank W = Weight of sample in grams Lactose Lactose content in the Peda samples was determined by Lane-Eynon method as per BIS (1989). 5 ml of Fehling solution A and 5 ml of Fehling solution B was taken in a titration flask. Then few drops of methylene blue indicator was added to it. Then it was titrated against 0.5 % lactose solution in ebullion conditions till the brick red colour was obtained. Then the same titration was repeated with solution of Peda of known dilution, made with water. Lactose content was obtained by comparing the titrating volume obtained in both the titrations Ash

39 Ash was determined as per AOAC, (1995). For estimation of ash about 3 gm of sample was taken in a previously dried and weighed silica crucible. It was heated over a hot plate till it was smoke free and then transfer to muffle furnace at 5500C for 5 hours. After cooling of the muffle furnace the crucible was taken out and weighed. Ash(%)= 100 x (W1-W2) W where, W - Weight of sample in gm W1 - Weight of silica crucible with ash in gm W2 - Weight of silica crucible Microbial Analysis (SPC) The pour plate method of BIS (1989) was followed to estimate the total plate count. For this readymade plate count agar media of Himedia Laboratories, Mumbai (Bombay) , India was used. For the preparation of media, 21.5 gm of PCA was dissolved in one litre of distilled water. The ph was adjusted to by using Sodium Hydroxide. Then,

40 it was sterilized by autoclaving at 1210C (15 psi pressure)for 15 minutes. The sterile molten media was maintained at 450C and was poured in Petri dish, inoculated with1.0 ml inoculum of a particular dilution. The plates were incubated at 37±1 0 C for 48 hours. The Petri plates having colonies between were selected for enumeration Storage Studies Free fat For free fat estimation the method described by Rangadham and Rajorhia (1989) was followed. Ten gram of sample after passing through a mesh of size 25 was placed in glass stopper conical flask, added with 100 ml petroleum ether and was shaken by tilting vertically 10 times. Then the petroleum ether was decanted in a beaker and heated on a hot plate to evaporate the petroleum ether. The beaker was placed at 1020C in an oven for 2 hours. After 2 hours the weight of beaker was noted and again put in the oven until constant weight was obtained. Free fat was expressed as the percentage of total fat in the sample Free Fatty Acid

41 The method of Koniecko (1979) was followed for the determination of FFA. Five gm of sample was blended for 2 minutes with 30 ml of chloroform in presence of anhydrous sodium sulphate. The contents were filtered through whatman # 1 filter paper into a 250 ml conical flask. Then titrated against 0.1N alcoholic KOH using phenolphthalein as indicator. The quantity of KOH consumed during titration was recorded. FFA content was expressed as oleic acid (per cent). FFA per cent = 2.82 x V/W Where V - W - Volume of 0.1N KOH required for titration in ml Weight of the sample (gm) Thiobarbituric Acid Value (TBA) The TCA extraction method of Strange et al. (1977) was followed. TBA value was determined by blending 20 gm of Peda with 100 ml of 20 per cent TCA and filtering it through whatman # 1 filter paper. A 5 ml aliquot of the TCA extract was mixed with 5 ml of 0.01 M2- thiobarbituric acid in test tubes. The test tubes were immersed in boiling

42 water bath for 30 minutes and the colour developed was measured as absorbance at 532 nm and TBA values were computed from the standard curve Peroxide Value For estimation of peroxide value (AOAC, 1995), 5 gm of sample was mixed with 20 ml mixture of chloroform : methanol (2:1) in pestle and mortar for 20 minutes. It was transferred to a beaker and kept overnight. Gently warmed in water bath, cooled and filtered through whatman # 1 filter paper. The filtrate was taken as lipid extract and in a conical flask mixed with 10 ml acetic acid : chloroform (3:2). Added 0.5 ml of saturated KI solution and 30 ml distilled water. Titrated with 0.01N sodium thiosulphate with vigorous shaking until yellow colour disappeared. Added 0.5 ml 1% starch solution and titrated until blue colour just disappeared. The peroxide value was given as: PV (meq/1000gm) = S x N x 1000 Weight of sample Where, S - ml of sodium thiosulphate

43 N - Normality of sodium thiosulphate solution Non Protein Nitrogen (NPN) The method of Rowland (1938) was followed to determine the NPN content in Peda samples by precipitating Peda with 15 per cent TCA and using filtrate for nitrogen estimation Sensory Evaluation Peda samples were evaluated for its sensory attributes such as flavour, body and texture, colour and appearance and overall acceptability by a panel of eight to ten trained and semi trained judges using 9 point hedonic scale (Nelson and Trout, 1964) Statistical analysis The data obtained was statistically analyzed for ANOVA with the help of computer program designed by Sheoran and Pannu, (1999).

44

45 CHAPTER IV RESULT AND DISCUSSION Peda is a popular indigenous milk based sweet. In addition to other factors the breakdown of fat is also responsible for spoilage and off flavour of peda. Use of antioxidants may prevent oxidation of fat. So the present study was undertaken to prevent fat oxidation in peda samples by using antioxidants. The results obtained during the course of investigation are presented and discussed in this chapter under following subheads: 2.1 Proximate composition of peda. 2.2 Selection of optimum concentrations of antioxidants. 2.3 Storage studies Effect of additives on the quality of peda during storage at 5 2 c Sensory quality Physico chemical quality SPC (log CFU/g) Effect of additives on the quality of peda during storage at 15 2 C Sensory quality Physico chemical quality

46 SPC (log CFU/g)

47 Table 1.Proximate composition of Peda Parameters % composition Moisture Fat Protein Lactose Ash 2.6 Results are the mean of the three replications.

48 Table 2. Selection of optimum concentration of tocopherol acetate and ascorbic acid for addition to Peda. Sensory score of overall acceptability of Peda stored at 25 ± 2º C tocopherol acetate sodium ascorbate Duration (Days) control 10ppm 12ppm 16ppm 400ppm 600ppm 800ppm Mean Mean Treatments CD (T) N.S. T Treatments, D Duration CD (D) 0.32 CD (T D) N.S.

49 2.1 Proximate composition of peda The proximate composition of peda varies considerably with the quality of milk used, method of preparation, degree of heat treatment, manner of handling of milk during preparation and quantity of sugar added to the peda. The results obtained for proximate composition of peda in the present study are given in Table 1. Peda had per cent moisture, per cent fat, per cent protein, per cent lactose and 2.6 per cent ash. 2.2 Selection of optimum concentration of antioxidants Peda samples were treated with tocopherol acetate and sodium ascorbate to the concentration of 10, 12 and 16 ppm and 400, 600 and 800 ppm, respectively. The samples were stored at 25 C and sensory evaluation was done at 5 days interval. All the spoiled after 14 days due to fungal growth. The results of sensory evaluation are presented in Table 2. Overall acceptability of all the treated samples was found to be equal. So the lowest concentration, that is 10 ppm of tocopherol acetate and 400 ppm of sodium ascorbate were selected for further studies.

50 Table 3. Effect of additives on color and appearance of Peda stored at 5 ± 2º C Treatments Duratio n (Days) C PS TA SA TA+PS SA+PS TA+SA TA+SA+PS Mean Mean CD (T) 0.06 T Treatments, D Duration CD (D) 0.06 CD (T D) N.S. C PS TA SA Control Potassium sorbate treated Tocopherol acetate treated Sodium ascorbate treated

51 Table 4. Effect of additives on body and texture of Peda stored at 5 ± 2º C Treatments Duratio n (Days) C PS TA SA TA+PS SA+PS TA+SA TA+SA+PS Mean Mean CD (T) 0.04 T Treatments, D Duration CD (D) 0.04 CD (T D) N.S. C PS TA SA Control Potassium sorbate treated Tocopherol acetate treated Sodium ascorbate treated

52 Table5. Effect of additives on flavor of Peda stored at 5 ± 2º C Treatments Duratio n (Days) C PS TA SA TA+PS SA+PS TA+SA TA+SA+PS Mean Mean CD (T) 0.04 T Treatments, D Duration CD (D) 0.03 CD (T D) N.S. C PS TA SA Control Potassium sorbate treated Tocopherol acetate treated Sodium ascorbate treated

53 . Table 6 Effect of additives on overall acceptability of Peda stored at 5±2º C Treatments Duratio n (Days) C PS TA SA TA+PS SA+PS TA+SA TA+SA+PS Mean Mean CD (T) 0.06 T Treatments, D Duration CD (D) 0.06 CD (T D) N.S. C PS TA Control Potassium sorbate treated Tocopherol acetate treated

54 SA Sodium ascorbate treated 2.3 Storage studies Effect of additives on the quality of peda during storage at 5 2 C Sensory quality a The results pertaining to sensory quality of peda samples are presented in Table 3. 4., 5. and 6. The interaction of treatments and duration was found to be non significant as for as changes in colour and appearance (Table 3, body and texture (Table 4.), flavour (Table 5.) and overall acceptability (Table 6.) are concerned. This shows that these factors are independent of each other and do not have any synergistic or antagonistic effect on sensory quality of peda b. Colour and appearance

55 There was significant decrease in colour and appearance of peda with time. (Table 3.). All the treatments except combination (tocopherol acetate + potassium sorbate) were found to be same in respect of changes in colour and appearance. Combination (tocopherol acetate + potassium sorbate) treated samples scored lowest points in respect of colour and appearance c Body and texture There was significant decrease in body and texture of peda with time in all the treatments (Table 4.). There was no significant difference among all the treatments except combination (tocopherol acetate + sodium ascorbate + potassium sorbate) treated samples. These samples scored lowest points in respect of body and texture of peda d Flavour There was significant decrease in flavour of all the samples of peda with time (Table 5.). There was significant decrease in flavour of peda in all the treatments e Overall acceptability

56 A significant decrease was noticed in overall acceptability of peda with time (Table 6.). Control and combination (tocopherol acetate + potassium sorbate) treated samples were found to be best. Table 7. Effect of additives on free fat (%) of Peda stored at 5 ± 2º C Treatments Duration (Days) C PS TA SA TA+PS SA+PS TA+SA TA+SA+PS Mea Mean CD (T) N.S. T Treatments, D Duration CD (D) 0.69

57 CD (D T) N.S. C PS TA SA Control Potassium sorbate treated Tocopherol acetate treated Sodium ascorbate treated Table 8. Effect of additives on FFA (%) of Peda stored at 5 ± 2º C Treatments Duratio n (Days) C PS TA SA TA+PS SA+PS TA+SA TA+SA+PS Mean Mean

58 CD (T) T Treatments, D Duration CD (D) CD (T D) N.S. C PS TA SA Control Potassium sorbate treated Tocopherol acetate treated Sodium ascorbate treated Table 9. Effect of additives on TBA value (mg malonaldehyde/kg) of Peda stored at 5 ± 2º C Treatments Duration (Days) C PS TA SA TA+PS SA+PS TA+SA TA+SA+PS Mea Mean

59 CD (T) T Treatment CD (D) D Duration CD (T D) N.S. C PS TA SA Control Potassium sorbate treated Tocopherol acetate treated Sodium ascorbate treated Physico-chemical quality a The results pertaining to changes in free fat, free fatty acids, thiobarbituric acid, non-protein-nitrogen and SPC are presented in Table 7, 8., 9., 10 and 11. respectively. The interaction between treatments and duration was found to be non significant as far as changes in free fat, free fatty acids, TBA value, NPN and SPC of peda are concerned. This shows that these factors are

60 independent of each other and have no synergistic or antagonistic effect on these parameters b Free fat There is no significant difference in all the treatments as for as changes in free fat are concerned. There was significant increase in free fat of peda with time in all the samples c Free fatty acids All the treatments except combination (sodium ascorbate + potassium sorbate) treated samples significantly reduced the changes in free fatty acids value of peda. Combination (sodium ascorbate + potassium sorbate) treated samples did not have any reducing effect on changes in free fatty acids of peda. Other samples except combination (sodium ascorbate + potassium sorbate) treated samples were equally effective in reducing changes in free fatty acids of peda. There was significant increase in free fatty acids value of all the samples of peda with time d TBA value There was significant increase in TBA value of peda with time. (Table 9). Both the treatments i.e. tocopherol acetate and sodium ascorbate