PROCESS OPTIMIZATION FOR MANUFACTURE OF READY-TO-RECONSTITUTE KHEER A THESIS SUBMITTED TO THE ANAND AGRICULTURAL UNIVERSITY IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF
Doctor of Philosophy IN
DAIRY TECHNOLOGY BY
HIRAL KUMAR MOHANLAL MODHA M. Tech. (D.T.) DEPARTMENT OF DAIRY TECHNOLOGY SHETH M.C. COLLEGE OF DAIRY SCIENCE ANAND AGRICULTURAL UNIVERSITY ANAND 388110 2016 Reg. No. 04 – 2072 – 2012
HIRAL KUMAR MOHANLAL MODHA
PROCESS OPTIMIZATION FOR MANUFACTURE OF READY-TO-RECONSTITUTE KHEER
BY
HIRAL KUMAR MOHANLAL MODHA M. Tech. (D.T.)
Ph.D. DAIRY TECHNOLOGY
DEPARTMENT OF DAIRY TECHNOLOGY SHETH M.C. COLLEGE OF DAIRY SCIENCE ANAND AGRICULTURAL UNIVERSITY ANAND 388110 2016
2016
Reg. No. 04 – 2072 – 2012
Dedicated To My Beloved Grand Father
PROCESS OPTIMIZATION FOR MANUFACTURE OF READYTO-RECONSTITUTE KHEER Name of Student
Name of Major Guide
HIRAL KUMAR MOHANLAL MODHA
Dr. S. V. PINTO
DEPARTMENT OF DAIRY TECHNOLOGY S. M. C. COLLEGE OF DAIRY SCIENCE ANAND AGRICULTURAL UNIVERSITY ANAND-388 110, INDIA
ABSTRACT
The present investigation was planned and conducted to arrive at a recipe and develop a technology for the manufacture of RTR kheer. The study was divided into nine phases which involved: Selection of variety of rice from Gujarat region for kheer manufacture (Phase 1); Optimization of pre-cooking and drying protocol for selected rice variety (Phase 2); Standardization of Fat/SNF ratio of milk and level of sugar for preparation of pre-mix powder (Phase 3); Optimization of proportion of precooked and dried rice and milk solids (Phase 4); Optimization of level of flavouring in ready-to-reconstitute kheer (Phase 5); Analysis of ready-to-reconstitute kheer for its compositional, physico-chemical, sensory, functional and microbial properties (Phase 6); Evaluation of shelf-life of the standardized RTR kheer (Phase 7); Computation of cost of production of the developed RTR kheer (Phase 8) and Consumer preference study of RTR kheer (Phase 9). In the first phase of the study, five major varieties of rice from central Gujarat region i.e. 3 aromatic, 2 non-aromatic rice were analysed for their chemical composition
and
physico-chemical
characteristics.
The
physico-chemical
characteristics of all the five selected varieties of rice were compared with that of basmati rice (C). Selected physical properties of rice of different varieties of central Gujarat region were examined viz. Thousand Kernel Weight (TKW), Kernel Length, Kernel Breadth, L/W Ratio. Cooking characteristics of rice viz. water uptake, Alkali
Abstract Spreading Value (ASV) and amylose content of various rice varieties were also investigated. Kheer, was prepared using the conventional method as described by Aneja et al. (2002). Certain quality parameters of kheer prepared using 3 aromatic, 2 nonaromatic rice varieties from Central Gujarat region and 1 control (Market basmati) were evaluated for moisture, fat, ash, total protein and total carbohydrate, viscosity and sensory attributes. Since, the flavour and total scores of the experimental samples of the kheer prepared from market basmati rice were statistically at par (P>0.05) with that of experimental sample of kheer prepared from GR – 101 variety, this variety was selected and used in in the next part of the study i.e. Phase 2 onwards. In Phase 2, optimization of pre-cooking conditions of GR-101 variety of rice was carried out with the objective of determining the best possible combination(s) of different levels of factors viz. pre-cooking temperature and pre-cooking time that would lead to the most acceptable product in terms of sensory scores. According to the suggested solution from RSM analysis, pre-cooking conditions of 87°C for 15 min was found most suitable for the manufacture of quick cooking rice. The selected precooking treatment was given after soaking the rice in pasteurized and cooled water which was maintained at 30°C for 30 min. After subjecting the rice to the selected precooking conditions, it was drained thoroughly and spread in a single layer on stainless steel trays and subjected to drying at 40±5°C and 740-760 mm Hg vacuum in a vacuum tray dryer. For manufacture of pre-mix powder which is a major constituent in terms of quantity for RTR kheer, in Phase 3, Two factors Response Surface Methodology (RSM) Central Composite Rotatable Design (CCRD) was used to optimize levels of Fat/SNF ratio and sugar (by weight of milk). The suggested solution from RSM analysis indicated that milk which was standardised to Fat/SNF ratio of 0.53, preheated to 90°C and condensed in vacuum pan up to 45 per cent total solids was found most suitable for manufacture of premix. The condensed milk was then dried in a pilot scale spray drier at 180°C inlet and 85°C outlet air temperature to get pre-mix. The pre-mix powder was then dry blended with 6.75 per cent sugar by weight of standardized milk.
ii
Abstract Traditional kheer comprises both the liquid and particulate phases. During kheer making, solids from rice or particulate phase ooze out in to milk phase and increase viscosity, total solids and gives characteristics aroma. To achieve similar consistency and aroma, it was decided that an optimum level of pre-cooked and dried rice was to be ground and added in the pre-mix powder. The quick cooking rice from Phase 2 and pre-mix powder obtained from Phase 3 were utilized in Phase 4 to optimize the rate of addition of pre-cooked rice (PCR), pre-cooked rice powder (PCRP) and total milk solids (TMS) in kheer using three factors RSM with CCRD. The suggested solution from RSM analysis for RTR Kheer was use of precooked rice @ 15.22 per cent, precooked rice powder @ 3.65 per cent and 30.94 per cent TMS in kheer. For optimizing the level of flavouring in RTR kheer, cardamom: nutmeg: saffron in the ratio 50:40:10 were selected as flavourings in RTR kheer in Phase 5. All the three flavourings (at different levels studied viz. 0.05 per cent, 0.075 per cent and 0.1 per cent) were dry mixed. The RTR kheer was reconstituted and the flavouring mix was added in to kheer during reconstitution at three different levels by weight of reconstituted kheer. It was found that maximum flavour score was observed with formulation having 0.075 per cent flavouring followed by 0.05 and 0.10 per cent flavouring. The final product was manufactured employing suggested formulation and the actual results were obtained from the RTR kheer manufacture. The predicted values of the criteria/responses selected for optimization under study were compared with the actual values of the selected responses. The results obtained confirmed that the selected combination was the best one in terms of the sensory, compositional and textural responses delineated at the beginning of the study and the results were also validated statistically. In the manufacture of RTR kheer, milk is standardized to 0.53 fat: SNF ratio, after checking its quality criteria. The standardized milk is heat treated to 90 °C and condensed to 45 per cent TS. The condensed milk is then spray dried known as pre-mix. Pre-mix is dry blended with 6.75 per cent sugar by weight of initial milk, 3.65 per cent pre-cooked rice powder by weight of pre-mix and 0.075 per cent flavouring mix and packed in Met-Polyester/Polyfilm pouches. On the other hand rice of GR-101 variety was soaked in water at 30°C for 30 min. Then pre-cooked at 87°C for 15 min and dried in vacuum tray drier at 45°C under 740-760 mm Hg iii
Abstract vacuum and packed in LDPE pouch at the rate of 15.22 per cent by weight of pre-mix. For reconstitution about equal amount of water to RTR kheer is taken and heated to 50°C and added slowly with pre-mix for dissolution. In another vessel pre-cooked rice is added to about three times its weight of boiling water. The rice is then allowed to boil for 5 min and then allowed to simmer for 5 more min to absorb almost all water. The cooked rice is added to the vessel containing reconstituted pre-mix. The mixture is subjected to boiling for a few seconds with intermittent stirring and scrapping so that it do not stick at bottom of vessel and allowed to cool at room temperature. The product may be garnished with saffron before consumption. Analysis of ready-to-reconstitute kheer for its compositional, physicochemical, sensory, functional and microbial properties was carried out in Phase 6. The average moisture, fat, total protein, ash and total carbohydrates of the standardized RTR kheer samples was 1.84 ± 0.15, 19.59±0.35, 14.35±0.74, 3.35 ± 0.04, 60.87 ±0.58 per cent, respectively. The product had had 0.582±0.01 per cent acidity in terms of lactic acid, 6.47±0.03 pH, 0.333±0.002 water activity, 0.085±0.001 per cent oleic acid (free fatty acid), total 50.59±2.99 µ moles /100g HMF and, 0.65±0.02 TBA value in terms of O.D. at 532 nm. The average flowability (s), bulk density, particle density (g/ml), interstitial air (cm3/100g), occluded air (cm3/100g), porosity (per cent v/v) and insolubility index (ml) of the standardized RTR kheer samples was found to be 122.3±1.5 sec, 0.743±0.004 g/ml, 1.389±0.00 g/ml, 63.59±1.03 cm3/100g, 24.11±0.20 cm3/100g, 60.57±0.21 (per cent v/v) and 2.13±0.15 ml, respectively. The mean values for standard plate count for fresh experimental samples of RTR kheer was 3.859±0.01 log10 cfu/g, whereas yeast and mould and coliform were absent in the fresh samples. The average flavour score (max. 45), consistency score (max. 35), colour and appearance (max. 15), package (max. 5) and total score (max. 100) of the reconstituted kheer made from fresh standardized RTR kheer samples was 42.64±0.36, 32.59±0.22, 13.87±0.15, 5.00±0.00 and 94.11±0.72, respectively. In Phase 7, the RTR kheer manufactured using the standardized process was evaluated for its shelf life at 37±2oC storage temperature and at the regular interval of 15 days after packing in Met-Polyester/Polyfilm pouches (~85μ). The acidity (per cent LA), pH, water activity(aw), free fatty acid (% oleic acid), total HMF (µ moles/100g), TBA value (OD at 532 nm), sensory, microbial quality (standard plate count, yeast and mould count, coliform count, thermoduric count and thermophilic iv
Abstract count) and functional properties (flowability (s), bulk density (g/ml), particle density (g/ml), interstitial air (cm3/100g), occluded air (cm3/100g), porosity (per cent v/v) and insolubility index (ml)) of stored samples of RTR kheer were evaluated. The product was rejected on sensory basis. During the course of storage study, flavour score of reconstituted kheer decreased below minimum prescribed value on score card i.e. less than 60 per cent at the end of 195 d. Based on the findings RTR kheer prepared by standardized method in the present study the product can be remained well acceptable up to 180 d of storage at 37±2oC temperature after packaging in MetPolyester/Polyfilm pouches (~85μ). The cost analysis was carried out in Phase 8, for the RTR kheer produced by utilization of 60 kg milk per batch giving 13.5 kg final product. The cost of raw materials required to preparing a batch of 13.5 kg RTR kheer was found ` 3118.52. The cost of utilities such as steam and packaging was ` 256.11. The overhead cost amounted to ` 674.93. Final cost of producing one batch of 13.5 kg of RTR kheer including raw material cost, cost of utilities and overhead cost of production was ` 4049.56 which when converted to per kg comes to ` 299.97. From 1 kg of RTR kheer about 1.865 kg of reconstituted kheer can be manufactured. In Phase 9, the RTR kheer prepared in a batch using the standardized recipe was evaluated for its commercial acceptance through a consumer survey. The consumer survey involved serving the RTR kheer to 160 consumers from Anand town, representing different segments of the society. The preference of consumers amply proved the marked superiority of the experimental product as compared to the market sample.
Therefore, the recipe and process standardized for RTR kheer
manufacture has potential to yield a product which could be very well accepted by the consumers.
v
SHETH M. C. COLLEGE OF DAIRY SCIENCE ANAND AGRICULTURAL UNIVERSITY ANAND- 388 110 (GUJARAT)
Dr. (Ms) S. V. Pinto Professor Department of Dairy Technology S. M. C. College of Dairy Science Anand Agricultural University Anand - 388 110, INDIA
This is to certify that the thesis entitled “PROCESS OPTIMIZATION FOR MANUFACTURE
OF
READY-TO-RECONSTITUTE
KHEER”
submitted
by
Mr. HIRAL KUMAR MOHANLAL MODHA (Registration No: 04-2072-2012) in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Dairy Technology of Anand Agricultural University is a record of bonafide research work carried out by him under my guidance and supervision and the thesis has not previously formed the basis for the award of any degree, diploma or other similar title.
Date:
/
/2016
Place: Anand
S. V. Pinto (Major Advisor)
Acknowledgement Although only one name appears as the author of this manuscript, the contents of this thesis would not have been possible without the effort, hard work, and support of many people. On the accomplishment of the present study, I would like to take this opportunity and words of appreciation towards those, who dedicated their today for my tomorrow. I deem it a proud privilege and feel immense pleasure to acknowledge all those who are directly or indirectly involved in enlightening me with the touch of their knowledge and extending me their unflinching support. It gives me immense pleasure to express my deepest sense of gratitude and reverence to my Major Advisor, Dr. S. V. Pinto, Professor, Dairy Technology Department and Former Major Advisor, Dr. H.G. Patel, Former Professor and Head, Department of Dairy Processing and Operation , SMC College of Dairy Science, AAU, Anand for their benevolence and erudite guidance, precious suggestions, innovative thoughts, consistent and invaluable encouragement, keen interest, critical supervision and all kinds of painstaking help extended to me that lead to successful completion of this project and win laurels. I consider myself as fortunate and greatly privileged to have worked under their supervision and guidance. It gives me immense pleasure to express my heartfelt gratitude to my Minor Advisor Dr. K. D. Aparnathi, Professor & Head, Dairy Chemistry Department, S.M.C. College of Dairy Science, A.A.U., Anand for his keen interest, invaluable guidance and profound support throughout my work tenure. I pay my due respect and thanks to Dr. J. B. Prajapati, Principal and Dean and Dr. B.P. Shah, Former Principal and Dean, S.M.C. College of Dairy Science, Anand for the help and facilities provided. I am immensely thankful to the members of Advisory Committee, Dr. A. H. Jana, Professor and Head, Department of Dairy Technology; Dr. J.P. Prajapati, Associate Professor & Head, Department of Dairy Processing & Operations and Dr. V. B. Darji, Associate Professor, Department of Agricultural Statistics, BACA, AAU, Anand for their keen interest, valuable suggestions, constructive criticism and ever willing help as and when required for the completion of the study. I express my heartfelt gratitude to Dr. P. S. Prajapati, Former Professor & Head, Dairy Technology Department, Dr. A.G. Bhadania, Professor & Head, Department of Dairy Engineering and Dr. A.K. Makwana, Professor & Head, Department of Dairy Business Management, SMC College of Dairy Science, AAU, Anand for their kind co-operation and technical suggestions. I also express my heartfelt respect and humble gratitude to Dr. A.J. Gokhale, Dr. Amit Patel, Mr. Chetan Dharaiya, Mrs. Jarita Mallik, Mr. Kunal Kadiya, Mr. Dhinal Patel and Mrs. Komal Patel, faculty members of Dairy Technology Department & Department of Dairy Processing and Operations for their constant encouragement, help and moral support during the course of this work.
I owe a deep sense of gratitude to assistant professors Dr. S. C. Parmar, Mr. Kunal Gawai, Mr. A. I. Shaikh, Dr. Smitha Balakrishnan, Mr. A. K. Jain, Mr. D. H. Patel, Mr. S. I. Patel, Mr. Kunal Kamani who directly and indirectly cooperated with me during the entire tenure of my doctoral degree. I owe a lot to the staff member Shri Dineshbhai M. Patel of Dairy Technology Department and Mr. V. L. Panchal, Mrs. Darshana Patni and Mr. Amit Barot from Department of Dairy Processing and Operations for providing necessary materials and support for my work. I am immensely thankful to Late Dr. A. M. Mehta, Research Scientist; Mr. S. G. Patel, Assistant Research Scientist, Main Rice Station, AAU, Nawagam for introducing me to the nuances of the rice and generously providing rice samples for the present study that helped in successful completion of this research work. I gratefully acknowledge the help rendered by Ms. M. U. Desai, Lab. Tech., Main Rice Station, AAU, Nawagam for the analysis of rice samples. My heart feels deeply indebted for the cordial co-operation and moral support extended by my beloved students and lab mates Ruchi, Akhila, Sakharam, Arjun, Chetna Mor, Chetna Chaudhary and Ekta. I am eternally indebted to my son Shlok and wife Minal for their sacrifices and unconditional love, support and constant encouragement. Thank you for always being there for me; I hope I make you proud! I am eternally indebted to my Parents Shri. Mohanlal A. Modha and Smt. Bhavnaben M. Modha and my brother Tejas and other family members for their blessings, inspiration and encouragement. I owe everything to Almighty Authority Supreme God, but for whom I would not have been anywhere now. I give all the glory, honour and praise to my Lord, whose abundant love and grace enabled me to travel throughout life and come to this stage. I am also grateful to all my well-wishers whom I might have failed to mention here. Date: / /2016 Place: Anand
(Hiralkumar Modha)
Contents Chapter 1. 2.
Title INTRODUCTION
2.REVIEW OF LITERATURE 2.1 INTRODUCTION 2.2 TRADITIONAL MILK CEREAL BASED PRODUCTS 2.2.1 Characteristics of Kheer 2.2.2 Payasam 2.2.3 Phirni 2.2.4 Shelf life of kheer and similar products 2.3 WESTERN MILK CEREAL BASED DESSERTS 2.3.1 Pudding type products 2.3.1.1 Hydrocolloids 2.3.2 Custard type products 2.4 CEREALS 2.4.1 Chemical composition of cereals 2.4.2 Cereals and nutrition 2.5 RICE 2.5.1 Rice Quality 2.5.1.1 Grain quality indicators 2.5.1.2 Cooking quality indicators 2.6 PROCESSING OF RICE 2.6.1 Cooking/ heating of rice in presence of water 2.6.2 Effect of soaking 2.6.3 Properties of cooked rice 2.7 QUICK COOKING RICE 2.7.1 Methods of manufacture of quick cooking rice 2.8 CONVENIENCE FOODS 2.8.1 Ready-To-Eat (RTE) Foods 2.8.2 Ready-To-Reconstitute (RTR) Foods 2.8.3 Ready to serve foods (RTS)/ Ready to use foods (RTU) 2.9 MILK BASED CONVENIENCE FOODS 2.9.1 Instant Kheer Mix 2.9.2 Instant Basundi Mix 2.9.3 Instant Mattha Mix 2.9.4 Gulabjamun Mix
Page No. 1-5 6-41 6 7 8 10 12 12 13 13 14 15 15 16 17 18 19 19 20 21 21 22 22 23 23 25 26 26 28 28 28 29 30 30
Chapter
Title 2.9.5 Instant Dalia Mix (Instant Wheat Porridge Mix) 2.9.6 Instant Multigrain Dalia Mix 2.9.7 Pearl millet based ready-to-reconstitute kheer mix
3.
Page No. 31 32 32
2.9.8 Cow pea based instant kheer mix 2.9.9 Instant Phirni mix powder 2.9.10 Ready-to-reconstitute carrot halwa mix 2.10 PACKAGING AND STORAGE OF DEHYDRATED FOODS 2.10.1 Packaging of hot air dried products 2.10.2 Physico-chemical changes occurring in dried dairy foods during storage 2.10.2.1 Non-enzymatic browning 2.10.2.2 Flavour related changes 2.10.2.3 Moisture 2.10.2.4 Fat oxidation 2.10.2.5 Colour
33 34 35
MATERIALS AND METHODS 3.1 MATERIALS USED IN RTR KHEER 3.1.1 Raw milk 3.1.2 Rice 3.1.3 Sugar 3.1.4 Condiments 3.2 TENTATIVE BASIC PROCESS FOR MANFACTURE OF KHEER 3.3 TENTATIVE PROCESS USED FOR MANFACTURE OF PRE-COOKED AND DRIED RICE 3.4 TENTATIVE PROCESS USED FOR RTR KHEER MANUFACTURE 3.5 TENTATIVE PROCESS USED FOR RECONSTITUTION OF RTR KHEER 3.6 RESPONSE SURFACE METHODOLOGY 3.6.1 Experimental plan and design for optimization of different variables for developing process for RTR Kheer manufacture 3.6.1.1 Experimental plan for pre-cooking and drying protocol 3.6.1.2 Experimental plan for standardization of pre-mix powder
42-72 46 46 47 47 47
36 37 37 38 39 39 40 41
48 49 50 50 50 52 52 52
Chapter
Title 3.6.1.3 Experimental plan for optimization of proportion of rice and milk solids 3.6.2 Adequacy of model 3.7 ANALYSES OF RICE 3.7.1 Moisture 3.7.2 Ash 3.7.3 Total Carbohydrates 3.7.4 Total protein 3.7.5 Fat 3.7.6 Thousands Kernel Weight (TKW) 3.7.7 Kernel Length 3.7.8 Kernel Breadth 3.7.9 L/W Ratio 3.7.10 Water Uptake 3.7.11Alkali Spreading Value 3.7.12 Amylose Content 3.7.13 Weight Gain 3.8 ANALYSES OF COMPOSITIONAL ATTRIBUTES RTR Kheer 3.8.1 Moisture 3.8.2 Fat 3.8.3 Total Protein 3.8.4 Ash 3.8.5 Total Carbohydrates 3.9 ANALYSES OF PHYSICO-CHEMICAL ATTRIBUTES OF RTR Kheer 3.9.1 Titratable Acidity 3.9.2 pH 3.9.3 Water Activity (aw) 3.9.4 Free Fatty Acids 3.9.5 5’-Hydroxy Methyl Furfural (HMF) 3.9.6 Thiobarbituric Acid (TBA) Value 3.9.7 Viscosity 3.10 SENSORY EVALUATION 3.11 MICROBIOLOGICAL ANALYSIS 3.11.1 Standard Plate Count 3.11.2 Coliform Count 3.11.3 Yeast and Mold Count 3.11.4 Thermoduric Count 3.11.5 Thermophilic Count
Page No. 53 54 55 55 56 56 56 57 57 58 58 58 58 58 59 60 60 60 61 61 62 63 63 63 63 64 64 65 65 66 66 66 66 67 67 67 67
Chapter
Title 3.11.6 S. aureus 3.11.7 Salmonella 3.11.8 Listeria monocytogenes 3.12 FUNCTIONAL PROPERTIES 3.12.1 Flowability 3.12.2 Bulk Density 3.12.3 Particle Density 3.12.4 Interstitial Air 3.12.5 Occluded Air 3.12.6 Porosity 3.12.7 Insolubility Index 3.13 STATISTICAL ANALYSIS
4.
3. RESULTS AND DISCUSSION 4.1 SELECTION OF VARIETY OF RICE FROM GUJARAT REGION FOR KHEER MANUFACTURE 4.1.1 Influence of varieties on proximate composition of rice 4.1.1.1 Moisture 4.1.1.2 Fat 4.1.1.3 Ash 4.1.1.4 Total Protein 4.1.1.5 Total Carbohydrates 4.1.2 Influence of varieties on physical properties of rice 4.1.2.1 Thousand Kernel Weight (TKW) 4.1.2.2 Kernel Length 4.1.2.3 Kernel Breadth 4.1.2.4 L/W Ratio 4.1.3 Influence of varieties on cooking characteristics of rice 4.1.3.1 Water Uptake 4.1.3.2 Alkali Spreading Value (ASV) 4.1.3.3 Amylose Content 4.2 INFLUENCE OF VARIETY OF RICE ON QUALITY OF KHEER 4.2.1 Influence of variety of rice on composition of kheer 4.2.1.1 Influence of variety of rice on moisture content of kheer
Page No. 67 68 68 68 68 69 69 70 70 71 71 71 73-186 74 76 76 76 76 77 77 77 80 80 80 80 82 82 83 83 85 86 86
Chapter
Title 4.2.1.2 Influence of variety of rice on fat content of kheer 4.2.1.3 Influence of variety of rice on ash content of kheer 4.2.1.4 Influence of variety of rice on total protein content of kheer 4.2.1.5 Influence of variety of rice on total carbohydrate content of kheer 4.2.2 Influence of variety of rice on viscosity of kheer 4.2.3 Influence of variety of rice on sensory attributes of kheer 4.2.3.1 Influence of variety of rice on colour and appearance score of kheer 4.2.3.2 Influence of variety of rice on consistency score of kheer 4.2.3.3 Influence of variety of rice on flavour score of kheer 4.2.3.4 Influence of variety of rice on total score of kheer 4.3 OPTIMIZATION OF PRE-COOKING & DRYING PROTOCOL FOR SELECTED RICE VARIETY 4.3.1 Influence of varying the level of pre-cooking temperature and pre-cooking time on the sensory properties of kheer 4.3.1.1 Colour and Appearance score 4.3.1.2 Consistency Score 4.3.1.3 Flavour Score 4.3.1.4 Total Score 4.3.2 Influence of varying the level of pre-cooking temperature and pre-cooking time on weight gain after cooking 4.3.3 Optimization of pre-cooking protocol for drying of rice 4.4 STANDARDIZATION OF FAT/SNF RATIO OF MILK AND LEVEL OF SUGAR FOR PREPARATION OF PRE-MIX POWDER 4.4.1 Influence of varying the level of pre-cooking temperature and pre-cooking time on the sensory properties of kheer 4.4.1.1 Colour and Appearance score 4.4.1.2 Consistency Score
Page No. 86 87 87 87 88 88 89 89 93 94 100 102 103 105 107 109 111 113 115
116 117 120
Chapter
Title 4.4.1.3 Flavour Score 4.4.1.4 Total Score 4.4.2 Influence of varying the level of Fat/SNF ratio of milk and level of sugar on viscosity of kheer 4.4.3 Standardization of Fat/SNF ratio of milk and level of sugar for manufacture of pre-mix powder 4.5 OPTIMIZATION OF PROPORTION OF PRECOOKED AND DRIED RICE AND MILK SOLIDS 4.5.1 Influence of varying the level of PCR and PCRP addition and TMS of reconstituted kheer on the sensory properties 4.5.1.1 Colour and Appearance score 4.5.1.2 Consistency Score 4.5.1.3 Flavour Score 4.5.1.4 Total Score 4.5.2 Influence of varying the level of PCR and PCRP addition and TMS of reconstituted kheer on the rheological properties 4.5.3 Optimization of product formulation for RTR kheer manufacture 4.6 OPTIMIZATION OF LEVEL OF FLAVOURING IN RTR KHEER 4.7 ANALYSIS OF STANDARDIZED READY-TORECONSTITUTE KHEER FOR ITS COMPOSITIONAL, PHYSICO-CHEMICAL, FUNCTIONAL, MICROBIOLOGICAL AND SENSORY PROPERTIES 4.7.1 Proximate chemical composition 4.7.2 Physico-chemical properties 4.7.3 Functional properties 4.7.4 Microbiological count 4.7.5 Sensory attributes scores 4.8 STORAGE RELATED CHANGES IN RTR KHEER 4.8.1 Effect of storage on compositional properties of RTR kheer 4.8.1.1 Moisture (%) 4.8.2 Effect of storage on physico-chemical properties of RTR kheer 4.8.2.1 Acidity (% Lactic acid) and pH 4.8.2.2 Water Activity (aW) 4.8.2.3 Free Fatty Acid (% Oleic acid) 4.8.2.4 Total HMF (µ moles /100g) 4.8.2.5 TBA value (OD at 532 nm) 4.8.3 Effect of storage on microbial attributes in RTR
Page No. 122 123 125
127 129 131 132 136 139 142 145 148 151
156
156 158 158 158 159 159 160 160 162 162 163 166 168 169 170
Chapter
Title kheer 4.8.3.1 Standard Plate Count (log10cfu/g) 4.8.3.2 Yeast & Mould Count 4.8.3.3 Coliform Count 4.8.3.4 Thermoduric count 4.8.3.5 Thermophilic count 4.8.3.6 Microbiological characteristics for RTR kheer 4.8.4 Effect of storage on sensory attributes in RTR kheer 4.8.4.1 Flavour score 4.8.4.2 Consistency Score 4.8.4.3 Colour and Appearance Score 4.8.4.4 Total Score 4.8.5 Effect of storage on functional properties of RTR kheer 4.8.5.1 Flowability 4.8.5.2 Bulk Density 4.8.5.3 Interstitial Air 4.8.5.4 Occluded Air 4.8.5.5 Porosity 4.8.5.6 Insolubility Index 4.9 COST FOR PRODUCTION OF STANDARDIZED RTR KHEER 4.9.1 Raw material cost 4.9.2 Cost of utilities 4.9.3 Overhead cost 4.9.4 Packaging cost 4.9.5 Final cost 4.10 CONSUMER ACCEPTANCE STUDY FOR RTR KHEER
5.
SUMMARY AND CONCLUSION 5.1 Selection of variety of rice from Gujarat region for kheer manufacture 5.2 Influence of variety of rice on quality of kheer 5.3 Optimization of pre-cooking & drying protocol for selected rice variety 5.4 Standardization of fat/SNF ratio of milk and level of sugar for preparation of pre-mix powder 5.5 Optimization of proportion of pre-cooked and dried rice and milk solids 5.6 Optimization of level of flavouring in RTR kheer 5.7 Analysis of standardized RTR kheer for its
Page No. 170 171 172 172 172 173 173 175 175 176 176 179 179 179 181 181 182 182 183 183 183 184 184 184 185 188-200 188 190 191 192 194 195 196
Chapter
Title compositional, physico-chemical, sensory, microbial and functional attributes 5.8 Storage related changes in RTR kheer 5.9 Cost for production of standardized RTR kheer 5.10 Consumer acceptance study for RTR kheer 5.11 Conclusion
Page No.
196 199 199 200
REFERENCES
i - xvii
APPENDICES
i - vii
LIST OF TABLES Table No.
Title
Page No.
2.1
Chemical composition of Kheer reported by different workers
9
2.2
Classification of Payasams
10
2.3
Chemical Composition of Payasams
11
2.4
Proximate composition of cereal grains (percent dry weight)
17
2.5
Comparative nutritive value of cereal grains
18
3.1
Rice cultivars used for manufacture of RTR kheer Experimental variables for Pre-cooking of rice (coded and actual values) Experimental variables for Pre-mix powder (coded and actual values) Experimental design matrix for optimization of pre-cooking of rice and optimization of pre-mix powder Experimental variables for RTR Kheer (coded and actual values)
47
54
3.8
Experimental design matrix for optimization of RTR Kheer Correlation between Alkali spreading value and Gelatinization temperature (GT) Flowability classification using a drum test for dairy products
4.1
Proximate chemical composition of selected rice varieties
78
4.2
Comparison of physical properties of selected rice varieties
81
4.3
Influence of varieties on cooking characteristics of rice Influence of rice variety on chemical composition and viscosity of kheer Influence of rice variety on sensory attributes of kheer Boundaries of the experimental domain and spacing of the compositional variables levels Central composite design matrix with the experimental data on sensory attributes and weight gain during pre-cooking of rice for response analysis Coefficient of the full second order polynomial model for coded sensory and processing responses to different levels of precooking conditions Criteria/responses chosen for optimization of pre-cooking conditions Suggested solution from RSM analysis for Pre-cooking conditions
84
3.2 3.3 3.4 3.5 3.6 3.7
4.4 4.5 4.6 4.7
4.8 4.9 4.10
52 53 53 54
59 69
90 95 102 108
108 113 113
Table No.
Title
Page No.
Comparison of predicted v/s actual values of responses used for optimization of Pre-cooking conditions Boundaries of the experimental domain and spacing of the compositional variables levels Central composite design matrix with the experimental data on sensory attributes and viscosity during pre-mix preparation for response analysis Coefficient of the full second order polynomial model for coded sensory and rheological responses to different levels of ingredients for pre-mix Criteria/responses chosen for optimization of pre-mix for RTR kheer Suggested solution from RSM analysis for Pre-mix of RTR kheer Comparison of predicted v/s actual values of responses used for optimization of Pre-mix Boundaries of the experimental domain and spacing of the compositional variables levels for RTR kheer Central composite design matrix with the experimental data on sensory and rheological attributes of RTR kheer for response analysis Coefficient of the full second order polynomial model for coded sensory and rheological responses to different levels of ingredients of RTR kheer Criteria/responses chosen for process optimization of RTR kheer
114
149
4.29
Suggested solution from RSM analysis for RTR Kheer Comparison of predicted v/s actual values of responses used for optimization of RTR Kheer Influence of level of flavouring on sensory attributes of RTR kheer Standardized RTR kheer Recipe Average proximate chemical composition, physico-chemical properties, functional properties, microbiological quality and sensory attributes of RTR kheer manufactured by standardized process Changes in composition of RTR kheer during storage Changes in physico-chemical attributes of RTR kheer during storage Changes in microbiological quality of RTR kheer during storage
4.30
Microbiological characteristics for RTR kheer
173
4.31
Changes in sensory attributes of RTR kheer during storage
174
4.32
Changes in functional properties of RTR kheer during storage
180
4.33
Raw material cost for preparing one batch (13.5 kg) of RTR kheer
184
4.11 4.12 4.13
4.14 4.15 4.16 4.17 4.18 4.19
4.20 4.21 4.22 4.23 4.24 4.25 4.26 4.27 4.28
116 119
121 127 127 128 130 133
134 149
150 151 153 156 161 167 171
Table No. 4.34 4.35 4.36
Title Cost of production for RTR kheer Rating of kheer as per the ‘Consumer Acceptance Trial’ with particulars of the respondents Frequency distribution for consumer acceptance (% of total consumers) on 9-point Hedonic scale for RTR kheer
Page No. 185 186 187
LIST OF FIGURES Figure No.
Title
Page No.
3.1
Various cultivars of rice used for study
48
3.2
Process for pre-cooking and drying of rice
49
3.3
Tentative process for manufacture of RTR Kheer
51
3.4
Tentative process for reconstitution of RTR Kheer
51
4.1
Proximate composition of rice varieties
79
4.2
Physical properties of rice varieties
82
4.3
Thousand kernel weight of rice varieties
82
4.4
Influence of varieties on water uptake of rice
84
4.5
Influence of varieties on alkali spreading values of rice
85
4.6
Influence of varieties on amylose content of rice
85
4.7
Influence of rice varieties on composition of kheer
91
4.8
92
4.10
Influence of rice varieties on viscosity of kheer Influence of rice varieties on colour and appearance score of kheer Influence of rice varieties on consistency score of kheer
4.11
Influence of rice varieties on flavour score of kheer
98
4.12
Influence of rice varieties on total score of kheer Influence of pre-cooking temperature and pre-cooking time on colour and appearance score of kheer Influence of pre-cooking temperature and pre-cooking time on consistency score of kheer Influence of pre-cooking temperature and pre-cooking time on flavour score of kheer Influence of pre-cooking temperature and pre-cooking time on total score of kheer Influence of pre-cooking temperature and pre-cooking time on weight gain of rice during cooking Influence of Fat/SNF ratio of milk and level of sugar on colour and appearance score of kheer Influence of Fat/SNF ratio of milk and level of sugar on consistency score of kheer Influence of Fat/SNF ratio of milk and level of sugar on flavour score of kheer
99
4.9
4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20
96 97
105 106 109 110 112 119 121 123
124
4.28
Influence of Fat/SNF ratio of milk and level of sugar on total score of kheer Influence of Fat/SNF ratio of milk and level of sugar on viscosity of kheer Influence of PCR, PCRP addition and TMS in kheer on the colour and appearance score of RTR kheer Influence of PCR, PCRP addition and TMS in kheer on the consistency score of RTR kheer Influence of PCR, PCRP addition and TMS in kheer on the flavour score of RTR kheer Influence of PCR, PCRP addition and TMS in kheer on the total score of RTR kheer Influence of PCR, PCRP addition and TMS in kheer on the viscosity of kheer Standardized process for manufacture of RTR Kheer
4.29
Standardized process for reconstitution of RTR Kheer
155
4.30
Composition (% w/w) of major constituents of RTR kheer Influence of storage period on compositional attributes of RTR kheer stored at 37±2°C Influence of storage period on physico-chemical attributes of RTR kheer stored at 37±2°C Influence of storage period on pH of RTR kheer stored at 37±2°C Influence of storage period on sensory attributes of RTR kheer stored at 37±2°C Influence of storage period on functional properties of RTR kheer stored at 37±2°C
157
4.21 4.22 4.23 4.24 4.25 4.26 4.27
4.31 4.32 4.33 4.34 4.35
126 136 139 142 145 148 154
164 165 166 177 178
LIST OF APPENDICES
Appendix No.
Title
Page No.
I
Buffer and Media for Microbiological Analysis
i
II
Buffer and Media for Pathogen Analysis
III
Score Card for Sensory Evaluation of Kheer
v
IV
Basis for Cost Calculation of RTR kheer
vi
V
9 - Point Hedonic Scale Score Card For Sensory Evaluation of Kheer
vii
ii-iv
LIST OF ABBREVIATIONS AND SYMBOLS
%
Percent
@
At the rate
°C
Degree Celsius
µ
Micron
µg
Microgram
AACC
American Association of Cereal Chemists
AAU
Anand Agricultural University
Al
Aluminum
Anon.
Anonymous
AOAC
Association of Official Analytical Chemists
APV
Adequate precision value
AR
Analytical reagent
ASV
Alkali spreading value
aW
Water Activity
BIS
Bureau of Indian Standards
C&A
Colour and Appearance
c.f.u
Colony forming unit
CCRD
Central Composite Rotatable Design
CD(0.05)
Critical difference at 5.0 per cent level
CHO
Carbohydrate
cm
Centimetre
Cm3 / cc
Cubic centimetre
CO₂
Carbon Dioxide
cP
Centipoise i
CRD
Completely Randomized Design
CV
Coefficient of variance
d
Days
DMB
Dry matter basis
e.g.
For example
et al.
And co-workers
etc.
Etcetera
FAO
Food and Agricultural Organization
FAOSTAT
Food and Agricultural Organization Statistics
FFA
Free fatty acids
FSSAI
Food Safety Standard Authority of India
g
Gram (s)
g/l
gram per litre
g/ml
Grams per millilitre
GT
Gelatinization temperature
h/hr
Hour
H₂O
Water
HMF
Hydroxy Methyl Furfural
IKM
Instant Kheer Mix
IS
Indian Standards
Kg
Kilogram (s)
kJ
Kilo Joule
kWh
Kilo Watt hour
L or l
Litre
L/W ratio
Length to width ratio
LA
Lactic Acid ii
LDPE
Low density polyethylene
M
Molar
Met-Polyester
Metallised Polyester
min
Minute
mm
Millimetre
mo
Months
m/sec
Metre per seconds
N
Normality, Newton
NaOH
Sodium Hydroxide
NS
Non-significant
OD
Optical Density
PCR
Pre-cooked & dried rice
PCRP
Pre-cooked & dried rice powder
PE
Polyethylene
PET/Polyester Poly ethylene terephthalate pH
Negative logarithm of hydrogen ion concentration
PP
Polypropylene
Ppm
Parts per million
R2
Coefficient of determination
RSM
Response Surface Methodology
RTE
Ready to eat
RTR
Ready to reconstitute
RTS
Ready to serve
RTU
Ready to use
S.Em.
Standard Error of mean
SD
Standard deviation iii
Sec
Seconds
SNF
Solid not fat
SPC
Standard Plate Count
spp.
Species
SS
Stainless steel
TBA
Thiobabituric Acid
TBARS
Thiobarbituric acid reactive substances
TKW
Thousand kernel weight
TMS
Total Milk Solids
TS
Total Solids
USDA
United States Department of Agriculture
v/v
Volume by volume
Viz.
Namely
VRBA
Violet Red Bile Agar
Vs.
Versus
w/w
Weight by weight
WHO
World health Organization
WMP
Whole milk powder
WPNI
Whey protein nitrogen index
YMC
Yeast and Mold count
iv
CHAPTER I INTRODUCTION India is the largest milk producing country with 138 MMT of milk production per annum accounting for ~ 16.3 per cent of the global milk production in 2013-14 (Beniwal and Kumaresen, 2015). India’s milk production is expected to grow to 153 MMT by the year 2020. Owing to their rich dietary qualities, the intake of dairy products has been increasing exponentially in the country. For the first time there is a record enhancement of milk production as 6.3 per cent whereas on international scenario there is only an increment of 2.2 percent enhancement of milk production in the year 2014-15 (MoA, 2016). Traditional Indian dairy products have not only served as an ethnic link with the modern dairy industry but also delivered a technological base for diversification and have a great export potential to make the modern dairy industry economically powerful to enable the milk producers get benefit from it. Market for such products is estimated to be about INR 50,000 crore. Traditional dairy products not only have established market in India but also great export potential because of strong presence of Indian diaspora in many parts of the world. Traditional dairy foods like cerealbased dairy desserts are confined to domestic kitchens because of lack of technological processes for their large-scale manufacture. Packaging of these products is almost non-existent. Traditional processes of preparing dairy desserts like kheer require good culinary arts and skills and are often inconvenient and time consuming. Approximately 1 to 2 hours are required to prepare kheer using conventional method. This, coupled with a lack of technology, has hampered its organized manufacture and marketing. India’s favourite dessert, Kheer, a sweet milk-rice confection is popular throughout the country. Hindu mythology refers to kheer or payasam, a milk cereal dessert, as the celestial nectar, ‘Amrit’ or elixir and gives it a place of prominence among foods as the secret of immortality. A variation of kheer, sometimes called Phirni, is made by using rice flour instead of granular rice. Though normally, connotation of kheer means a milk-rice based product. Several variations in kheer includes products based on wheat (dalia), semolina, pearl millet, makhana, etc.
Introduction Conventional process for manufacturing each of these variations is almost similar except for the raw material being used. The short shelf life has been a major deterrent in large-scale commercial manufacture and marketing of kheer in the traditional form. The shelf life of kheer when hot packed in tin cans was found to be only 2-3 days at 37°C that could be extended to up to 8-10 days by employing nisin as a preservative (Aneja et al., 2002). The manufacture of kheer in a dry form suitable for ready reconstitution could help overcome the problem of its shelf life. Moreover, because of changing food habits and burgeoning middle class and the improved life style, convenience foods are fast gaining popularity with the increase in rate of urbanization in India. Convenience foods have also been described as foods that have been created to "make them more appealing to the consumer. It is a food, typically a complete meal that has been preprepared commercially and so requires minimum further preparation by the consumer. Today, large scale production, consumption and utilization of newer food products with added convenience, better shelf life and attractive packaging is gaining market. Several traditional foods having poor shelf life can be converted into dehydrated form for enhanced shelf life and improved commercial value. In literature scanty information is available on the ready-to-reconstitute kheer mixes. Jha et al. (2002) developed a process for the manufacture of Instant Kheer mix powder using fluidized bed drier for drying of rice grains. Kadam et al. (2011) developed a formulation of ready-mix kheer using finely ground Basmati rice of uniform grain size, powdered cane sugar and whole milk powder (WMP) in different proportions. These researchers used ground basmati rice in the formulation which would not have the same body and textural attributes of kheer. Since there is very scanty information available on the ready-to-reconstitute kheer mixes, the present work was planned and undertaken to develop a suitable formulation for ready-toreconstitute kheer mix. Rice Rice (Oryza sativa) is a dietary staple foods and one of the most important cereal crops, especially for people in Asia, but the consumption outside Asia has increased, recently (Orthoefer, 2005). The unique taste of rice provides easy way to combine rice with the other food to achieve better taste and nutritional balance 2
Introduction (Orthoefer, 2005; Roy et al., 2008; USDA, 2011). Market quality of rice depends upon the size, shape, whiteness and aroma. The cooking quality of rice depends on the amylose content, gelatinization, water intake, gel consistency and texture of cooked rice. Various quality criteria have been used to assess the suitability of rice for kheer making such as amylose content, gel consistency, whiteness, water uptake capacity, etc. The amino acid profile of rice shows that glutamic and aspartic acids are the major amino acids present in rice, while lysine is the limiting amino acid (FAO, 2004). Rice is a good source of thiamine (vitamin B1), riboflavin (vitamin B2) and niacin (vitamin B3). Although rice is rich of nutrients, rice alone cannot supply all of the nutrients which are necessary for adequate nutrition. It needs to be complemented with the other food. Animal products and fish are useful addition to the diet, as they provide large amounts of essential amino acids and micronutrients. Pulses, such as beans, groundnuts and lentils, are also nutritional complements to the rice-based diet and help to complete the amino acid profile (FAO, 2004). Use of cereals combined with milk in form of palatable foods deal with both nutrition and healthfulness. In view of cereal-based milk foods managing greater acceptance for their health benefits and economic concerns, the major task that lies ahead is to integrate these basic ingredients into products that appeal to the sophisticated palates of our modern society and also provide convenience to the fast paced lives of individuals. To retain more thiamine, rice should be not highly milled. However, people usually prefer polished rice (WHO, 1999). The processing method such as parboiling and milling influences the variability of rice nutrients content (Roy et al, 2008). Several types of rice (commercial samples of brown, parboiled brown, parboiled milled and milled rice) had similar protein and crude fat contents, however, the ash contents among types of rice were slightly different, mainly among milled samples (Heinemann et al., 2005). Aromatic rice varieties such as Basmati, Muskan, Badsha and Bhog are classified on the basis of kernel dimension, with a premium price for their aroma. However, they are seldom useful for producing kheer. Generally, short, broken rice is used in kheer making. Need for development of convenience foods There is a need to simplify and standardize the processes of preparing traditional dairy products, which would not only require lesser preparation time but 3
Introduction also, would be convenient to use. This is possible by standardizing the processes for formulation of ready-mixes and ready-to-eat or ready-to-serve dairy products. Several preparations of convenience foods for different milk based products are available in the market which can be very conveniently used. However, limited attempts have been made to develop/ formulate the ready-mixes for Kheer. Most important features of rice suitable for kheer making are whiteness, grain size and shape, hardness of endosperm, amylose content, gel consistency and protein content. The nutrients content of rice were varies depending on the variety of rice soil, and the conditions they growth. Several varieties of rice have been developed by the Anand Agricultural University and the physic-chemical characteristics have been studied. Studies on suitability of varieties of rice grown in Gujarat region for kheer making have not been investigated in literature. The method used for precooking of rice and drying conditions greatly influences the body and texture characteristics of the grain. Jha et al. (2002) developed a process for the manufacture of Instant Kheer mix powder using fluidized bed drier for drying of rice grains. However, drying of rice grains using vacuum tray drier has not been studied yet. It is envisaged that use of vacuum tray drier would be a cheaper and feasible technology for small scale entrepreneurs. Hence, the present research work has been planned keeping in view standardizing the selected manufacturing parameters such as variety of rice, additives/ingredients and drying parameters to upgrade the manufacturing process and have desired sensory properties. On the basis of the outcome of the experiment, it would be possible to upgrade the existing standardized methodology for the manufacture of Ready-to-reconstitute Kheer. Therefore, this research work was planned with the following specific objectives:
(a)
To select scented varieties of rice of Gujarat region for kheer manufacture. 4
Introduction (b)
To optimize pre-cooking and drying protocol for selected rice variety.
(c)
To standardize Fat/SNF ratio for milk and levels of sugar for ready-toreconstitute kheer.
(d)
To optimize proportion of precooked, dried rice and dried milk solids.
(e)
To optimize levels of flavouring in Ready-to-reconstitute Kheer.
(f)
To analyse the product mix for its compositional, physico-chemical, sensory, functional and microbial properties.
(g)
To evaluate the shelf life of standardized product mix.
5
CHAPTER II REVIEW OF LITERATURE 2.1 INTRODUCTION Consumer preference and technological innovations are the forces acting as catalysts for change in dairy and food industry. In the last few years increase in population, urbanization, education and communication drove the food industry towards convenience along with health consciousness. Ready-to-eat food products aimed at supplying to the sectors like defence personnel in challenging conditions, traveling people and upwardly-mobile city dwelling executives are a fast developing trend. The Indian subcontinent is one the few regions in the world where consumption of milk and milk products is historically imbibed in its culture. Use of milk and milk products has been quoted in epics. India’s market potential for traditional dairy products is incomparable and all set to thrive further under the technology of mass production. An estimated 50 to 55 per cent of the milk produced in India is converted into a variety of traditional milk products, using processes such as coagulation, desiccation and fermentation (Thote et al., 2016). Cereal based desserts are very popular both due to their taste and nutritional value (Jha, 2000). Kheer is one such Indian traditional dessert prepared by partial dehydration of whole milk, with sugar and rice added to it, in an open pan over direct fire (De et al., 1976). Kheer is considered to be a good source of proteins, minerals, vitamins and other nutrients. Mani et al. (1955) reported that 100 g of kheer contains: 388 mg calcium, 237 mg phosphorus, 3.4 mg ascorbic acid, 118 mg thiamine, 242 IU vitamin A, 277 µg nicotinic acid and 353 µg riboflavin. However, like other indigenous products, kheer is a highly perishable product and suffers from limited shelf life, largely because of its high moisture content (60 to 70 per cent). The shelf life of kheer is reported to be only 3-4 days at refrigeration temperature (Jha, 2000). Most of the commercially available kheer mixes contain broken rice or rice flour, which upon reconstitution do not give the desired texture and mouthfeel of kheer. Thus, dry mix formulation of kheer requires attention in this direction.
Review of Literature At present there is a limited availability of milk based convenience foods in the market. Considering milk as a perishable commodity, a large scope exists for production of instant mixes made out of milk to be converted in to actual product with very less cooking before consumption. Moreover, dried products would require lower packaging, storage and distribution cost, because of reduction of bulk water and eradication of refrigeration for storage and transport compared to the reconstituted products. India is located amidst milk deficit countries in Asia. Because of the low cost of production of milk and availability of surplus milk in India, there is a great scope to export milk based convenience products to the neighbouring countries as they also have similar traditional products, but don’t have technology to produce it at large scale and extending the shelf life (Thote et al., 2016). 2.2 TRADITIONAL MILK CEREAL BASED PRODUCTS About 50 per cent of the milk produced in India (~138.0 MMT) is converted into traditional dairy foods. Traditional dairy foods include cereal-based dairy desserts, which are confined to domestic kitchens because of lack of technological processes for their large-scale manufacture. Packaging of these products is almost non-existent. Market for such products is estimated to be about Rs. 50,000 crore (US$ 10.29 billion). Most of these products are consumed locally as they suffer from poor shelf life. Recent focus is on developing new and innovative processes for converting these traditional dairy foods into convenient formulations so that shelf life is enhanced and there is an ease of consumption (Jha and Patel, 2014). Cereal based dairy desserts may be obtained from rice or wheat in different forms viz., broken or whole grains, grain fractions like semolina and cereal flour. However, the product containing grains especially rice grains is very common and traditionally the most popular. Hindu mythology refers to kheer or payasam, a milk cereal dessert, as the celestial nectar, ‘Amrit’ or elixir and gives it a place of prominence among foods as the secret of immortality. Since time immemorial, kheer has maintained its place of prominence in Indian diet and no festival is complete without kheer as a dessert.
7
Review of Literature 2.2.1 Characteristics of Kheer Kheer is a product obtained by cooking of rice in milk during concentration. Kheer, Payasam and Phirni are some of the common terms used to describe the product in different parts of the country. It may contain other cereals like wheat, pearl millet, ragi or sago. It may even contain pulses and vegetables or fruits in some parts of country. But, generally kheer is recognized as sweetened product having a thick consistency resembling rice pudding commonly consumed in western countries (Aneja, 1997). At present there is no legal definition for kheer in India. Mani et al. (1955) one of the earliest workers on kheer, reported the nutritional value of kheer made using traditional method from rice and milk. The product had a fat percentage of 4.1 per cent and 12.5 per cent total solids (TS). The traditional method of kheer preparation involves immersion of pre-soaked rice in simmering milk (6 per cent) added with sugar (6 – 8 per cent) and finally heating the mixture till rice softens up and shows signs of gelatinization, leading to significant thickening. Chopped nuts and cardamom are then finally added (Aneja et al., 2002). The method of kheer making has undergone very limited modification i.e. open pan concentration using direct fire has been replaced by steam jacketed kettle. De et al. (1976) were the first to manufacture kheer using a steam jacketed kettle. They made kheer from cow milk (4.0 per cent fat) using 2.4 per cent pre-soaked rice and 5.0 per cent sugar. Later, Chaudhary (1989) observed that the best quality kheer can be prepared from buffalo milk having 5.0 per cent fat and 9.7 per cent SNF and added with 5.0 per cent rice and 12.0 per cent sugar. In attempts to modify the kheer making process, he also found that an acceptable product can be obtained by mixing diluted sweetened condensed milk (30 per cent TS) with pre-cooked rice (6.0 per cent). De et al. (1976) reported that the total solids, fat, protein, lactose, ash and sucrose of kheer was 32.98, 7.83, 6.34, 8.45, 1.41 and 8.95 per cent respectively. While the corresponding values reported by Chaudhary (1989) for the same kheer were 38.23, 6.38, 5.44, 6.49, 0.74 and 14.74 per cent respectively in addition to 4.45 per cent other carbohydrates. The proximate composition of kheer studied by various authors is represented in Table 2.1.
8
Review of Literature Table 2.1 Chemical composition of Kheer reported by different workers (Per cent by wt.) Constituents Mani et al. (1955)
De et al. (1976)
Chaudhary (1989)
Total solids
31.00
32.98
38.23
Fat
12.20
7.83
6.34
Protein
5.90
6.34
5.44
Lactose
11.30
8.45
6.49
Ash
2.30
1.41
0.74
Sucrose
-
8.95
14.74
Other
-
-
4.45
carbohydrates Jha et al. (2002) formulated an instant kheer mix powder mix having the following composition: 1.91 per cent moisture, 18.22 per cent fat, 15.31 per cent protein, 2.51 per cent ash and 62.71 per cent carbohydrates. Chaudhary (1989) reported that sensory scores of kheer improved from 6.9 to 8.5 (on a 9 point hedonic scale) as the milk fat content increased from 3.0 to 5.0 per cent. Bandopadhyay (1995) studied the rheological parameters of kheer with respect to effects of rice variety and cooking time. Higher visual consistency and lower grain hardness led to higher body and texture score of Basmati rice kheer. Viscosity of the milk rice mixture increased logarithmically with increase in total solids content of kheer. However the overall textural acceptability of kheer was decided by both liquid phase viscosity and cooked grain tenderness. Jha et al. (2011) compared the traditional and developed long life kheer which was processed at very high temperatures using rotary retort. There was a drastic reduction in all the sensory attributes i.e. colour and appearance, texture, flavor and overall acceptability of long life kheer i.e. 6.92, 8.00, 7.26 and 7.54 compared to scores obtained for traditional kheer i.e. 8.50, 8.66, 8.50 and 8.50 on 9-point hedonic 9
Review of Literature scale respectively. The reduction in sensory score was attributed to processing of long life kheer at very high temperatures in the rotary retort. Jha et al. (2002) correlated the sensory scores of traditional kheer with reconstituted kheer made from instant kheer mix. They observed that the reconstituted kheer was found to be better than traditional kheer in terms of colour score (8.75 vs 8.50), while flavour and overall acceptability were almost similar (8.25 vs 8.50 and 8.37 Vs 8.50 respectively), but the texture score was less (7.09 vs 9.00) on 9 point hedonic scale due to greater hardness, coarseness and stickiness in the reconstituted kheer. 2.2.2 Payasam Payasam, a popular variety of milk rice based dessert in Kerala.
It
is
a
traditional sweet delicacy similar to Kheer. The colour of Payasams varies from white, light cream, cream, light brown to brown. The consistency of different varieties of Payasams varies from free flawing to soft-solid state. Many varieties have pleasant cooked flavour. Some varieties give added nutty / fruity flavour. Cardamom is one of the most popular flavouring used. Based on the characteristic ingredients, the Payasams are classified as pulse, cereal, and cereal product, tuber crop product, fruit and seed based. The characteristic ingredient and the specific names of the Payasams having various suspended solids are given in Table 2.2 Table 2.2 Classification of Payasams Sr. Type No 1. Pulse based
Characteristic Ingredient Bengal gram dhal, Green gram dhal Rice, wheat
2.
Cereal based
3.
Cereal product Beaten rice, suji, based vermicelli, ada
4.
Tuber product Sago based Fruit-based Mango, jack fruit Seed-based Poppy
5. 6.
Specific Name Kadale Bele, Parippu, Hesaru Bele Halu Kheeru, Pal, Gil-EFirdaus, Godhi Avalakki, Happala Kuthida, Rave, Akki Nutchu, Phirni, Shyavige,Palada,Shir Kurm Sabbakki, Kaddu ki Kheer Mavina, Halasina Khus Khus (Gasa gase) (Unnikrishnan et al., 2000)
10
Review of Literature Among cereal based Payasams, rice and wheat based are very popular. Some of common types includes Palada Payasam and Pal Payasam. Thirattu Pal is a popular delicacy in Tamil Nadu and Palada is the most popular Payasam in Kerala (Unnikrishnan et al., 2000). Soaked rice is ground to a fine paste with coconut and cardamom and same is then cooked in milk during preparation of Halu Kheeru. Finally, the product is garnished with good amount of dry fruits. Rice used in Halu Kheeru Payasam is about one fifteenth of milk by weight. Godhi Payasam is prepared in the same manner of Halu Kheeru Paysam but rice is replaced with wheat. A detailed information on the composition of a variety of Payasams has been reported by Unnikrishnan et al. (2000) and the same is included in the Table 2.3. Table 2.3 Chemical Composition of Payasams Weight per cent Payasam
Total
Suspended
Solids
Solids
Kadale bele
48.1
Hesaru bele
Fat
Protein
Lactose
Sucrose
25.8
3.2
6.4
2.2
24.2
42.4
16.1
1.7
5.5
2.4
22.7
Halu kheeru
38.4
14.4
2.3
1.9
2.6
19.9
Pal
43.1
7.8
3.7
3.4
4.1
24.6
Gil-E-Firdaus
39.2
-
7.8
7.7
8.9
11.2
Godhi
42.4
12.8
3.4
2.6
1.8
21.9
Avalakki
35.2
8.8
3.7
2.8
1.8
17.7
Akki Nutchu
39.8
4.0
1.4
2.2
1.9
21.6
Rave
40.1
5.1
3.5
2.3
1.9
20.8
Shyavige
30.9
4.8
1.8
1.8
1.9
20.8
Shir-Kurma
36.5
5.8
3.4
3.3
6.2
17.8
Palada
51.9
6.2
3.7
4.2
4.9
32.0
Kaddu ki Kheer
40.1
11.9
1.1
1.2
2.6
22.7
Halasina
32.4
3.1
2.0
1.7
2.5
22.9
Mavina
31.2
-
1.4
1.6
2.8
20.6
Khus Khus
40.0
-
7.2
6.2
2.4
20.3
(Unnikrishnan et al., 2000)
11
Review of Literature 2.2.3 Phirni Phirni have similar product profile as Kheer or Payasam which contains granular rice instead of rice flour. It is one of the oldest rice puddings in Middle-East or Persia which was brought to India by the Moghuls in 14th century. It is conventionally prepared by cooking of rice in the form of paste/flour/suji with buffalo milk along with cane sugar and other additives like cardamom powder, cashew powder, rose water, colour etc. The final texture comes due to the prolonged boiling with continuous stirring till it thickens. Finally, it is packed in earthen pots/cups, cooled to room temperature and stored at refrigerated temperature (4°C) before serving (Kumar et al., 2015). 2.2.4 Shelf life of kheer and similar products Poor shelf life of kheer has been a major bottle neck in its commercial production. De et al. (1976) estimated the shelf life of kheer, hot filled in tin cans. The shelf life was found to be only 2-3 d when stored at 37°C and could be extended up to 3-4 d by providing thermal treatment, and up to 8-10 d by using nisin as preservative. Chaudhary (1989) observed the shelf life of kheer made using steam kettle to be only 8 h at 30°C and 9 d at 5°C. Use of sodium-meta bisulphite could not substantially increase the shelf life of kheer at 30°C. Singh et al. (1987) reported an increase in shelf life of thermally processed kheer to about 6 months at room temperature by using nisin at a concentration of 200 IU/g product. In-pouch sterilized kheer in ready-to-eat form with shelf-life of 4 mo. at 37°C was reported by Jha (2000). The average TS, fat, protein, total ash and carbohydrate content of the product were 32.78, 7.98, 10.86, 1.47 and 12.47 per cent respectively. Jha et al., (2011) developed a method for manufacture of long life ready-toserve kheer. The kheer was made from basmati rice brokens and cow milk (3.0 per cent fat and 8.5 per cent SNF). The mixture was pre-concentrated to various levels and sterilized in counter pressure rotary retort at 121.1°C at a speed of 2 rpm after filling in retort pouches. Such retort processed kheer had a shelf life of 115 d at 37°C. In-pouch sterilized palada payasam having shelf life of 28 d at 37° and 55°C was reported by Patel (2004). The chemical composition of the payasam was 42.5 per cent total solids; 3.96 per cent fat; 3.90 per cent protein and 0.67 per cent ash. The 12
Review of Literature physico-chemical characteristics of the palada payasam ranged from 0.955 -0.967 for aW, 6.28 - 6.34 for pH, 0.18 - 0.22 (per cent LA) for acidity and the Hydroxy methyl furfural content ranged from 19.8 - 42.1 moles/lit. Dietetic chhana kheer having shelf life of 90 d at 37 °C was developed with multiple artificial sweeteners processed at 121.40°C for 20 min (Gautam et al., 2014). A process for manufacturing chhana kheer based on milk fat, aspartame, acesulfameK and sucralose was optimised. Aspartame and acesulfame-K at the level of 0.015 per cent and sucralose at the level of 0.05 per cent were found to be the most appropriate levels for chhana kheer (Gautam et al., 2012). 2.3 WESTERN MILK CEREAL BASED DESSERTS The term ‘dairy desserts’ refers to a sweet products, made out of milk and/or cream, which are thickened or gelled by use of suitable gelling agent. Dairy desserts are source of considerable value addition for dairy industries worldwide. A range of milk based desserts are available in variety of textures, flavours, colour and appearance ranging from simple rice pudding to multi layered custards. 2.3.1 Pudding type products Certain processes developed in the West relates to similar or related products, like ‘Milch Reis’ from Germany (meaning milk-rice) and rice pudding. In one such process the rice grains were cooked in saturated steam at a pressure higher than atmospheric pressure in an autoclave for time sufficient to gelatinize a major portion of rice starch. The resultant rice grains were mixed with milk for consumption in the form of product similar to kheer (Galle et al., 1984). Eibel (1986) reported the use of Contherm scrapped surface heat exchanger (CSSHE) for the production of milk and rice based pudding. Rice and milk were pumped in to the CSSHE system, heated to 115°C and held at same temperature for 26 min in a holding tube and then cooled down to 80°C in another contherm SSHE. The prepared rice pudding was then transferred to sterile tanks and finally filled in to plastic pots. A dairy dessert “creamed rice” was reported by Keogh (1970, 1971) in which short-grained rice, realising starch on cooking was used in combination with homogenized milk and sugar. The mixture of rice, sugar and milk was optimally mixed with stabilizer, colour, flavour and the product was sterilized at 121°C for 13 to 22 min. for enhancing the shelf-life to about 12 mo. at 27 °C. 13
Review of Literature A rice pudding was made by Kester and Matz (1970) using sterilization at 137.8°C for 30 – 60 s. The two components of rice pudding, the rice grains in small amount of liquid and a sauce, were sterilized individually and then combined in a can as both the components required different sterilization treatments. In a process of flame sterilization for rice pudding manufacture, the pudding mix was packed in cans, which were immediately closed and run in to the heating section at 137.8°C for 40 – 60 s. This method was found highly successful for canned milk-rice pudding (Casimier and Lewis, 1972). Murtaugh and Murtaugh, (1994) developed a milk rice based frozen dessert in which, cooked rice grains are mixed with sufficient liquid so as to form a mixture having a composition of about 30 to 70 per cent cooked grain by weight with a moisture content of 50 to 85 per cent. Sweetening and flavouring agents are added to this mixture. The mixture is then homogenized and frozen with until a temperature of about -9.5° to -5.5°C is obtained. 2.3.1.1 Hydrocolloids The preparation of milk based desserts often requires addition of hydrocolloids or gelling agent to get desired consistency in the final product. The texture of gelled product also depends on the type and quality of hydrocolloid used. The composition of dessert, its pH and processing conditions should be taken in to consideration for selection of suitable hydrocolloid. The gelling and thickening properties of starch had very positive influence on functional and sensory properties of milk cereal based foods like puddings, desserts and confectionary products. They also provide dietary fibre, which is lacking in only milk based products (Glicksman, 1982).
A
combination of starch with high lauric acid containing fat was used to formulate a pudding, which had a low viscosity after cooking and sterilization and during packing, but a desired high viscosity, texture and mouthfeel at refrigerated storage (Joseph et al., 1988). King and Leshik (1993) developed a process for manufacture of ready-to-eat, low fat puddings in which fat was replaced partially by calcium sensitive, thermally irreversibly gelling hydrocolloids like sodium alginate. Leshik et al. (1990) developed an aseptically processed and packed aspartame containing milk based pudding having pH 5.5 to 5.7. Kadan and Zeigler (1990) developed a pudding like product containing 14
Review of Literature milk, sweetener, rice flour, carrageenan, pectin, locust bean gum, whey protein isolate, xanthan gum and tetra-potassium pyrophosphate. 2.3.2 Custard type products Custards are a popular desserts in many parts of world. Similar foods also known as flans, made from milk and hydrocolloids is being used in several parts of world. Such foods are having great potential to be utilized as snacks, desserts or even meal replacements (Kadan and Zeigler, 1989). Direct UHT sterilized custards were made by employing sterilization at 142°C for 2 to 6 s, which were having shelf life of 4 mo. at 20°C. Packaging of custards in a laminate of paper, Al foil and polyethylene has been reported to have a shelf life of 3 mo. (Driessen et al., 1981). Mottar (1989) developed a UHT Processed, ready-to-serve, custard type milk based dessert containing wheat starch. Vanilla flavoured custards were made using Xanthan gum, CMC and a blend of kappa, lambda & iota carrageenan and 5 modified starches. The custards were subjected to direct and indirect UHT processing. The custards were then aseptically filled in to sterile packages and stored at 35°C. Singhal and Kulkarni (1990) compared the quality of custard made from Amaranthus paniculatus (Rajgeera) and that of one made from corn starch. It was reported that Rajgeera custard was having higher viscosity than corn starch custard, while addition of sugar decrease the viscosity of Rajgeera custard more than corn starch custard. 2.4 CEREALS Cereals have a long history of use by humans. Cereals are basic or fundamental foods, and are important sources of nutrients all over the world. The global importance of cereal crops to the human diet cannot be over stated. Cereal grains are the fruit of plants belonging to the grass family (Gramineae). Cereals and cereal based products are significant sources of energy, carbohydrates, protein and fibre, along with micronutrients like vitamins and minerals. Cereals and cereal based products may contain a variety of bioactive substances and there is developing interest in the prospective health benefits they may offer.
15
Review of Literature Cereal grains constitute major source of dietary nutrients. American Association of Cereal Chemists (AACC) International (1999) defines “whole grain” as “the intact ground, cracked or flaked caryopsis, whose principal anatomical components, the starchy endosperm, germ, and bran, are present in substantially the same relative proportion they exist in the intact caryopsis”. FAO (2016) forecasted world cereal production to 2,521 MMT, of which rice accounts for 495 MMT, which is about 20 per cent of cereal production which is second to wheat. Other major cereal crops produced include sorghum, oats, millets and rye. Asia, Americas, and the Europe produce more than 80 per cent of the world’s cereal grains. Wheat, rice, sorghum, and millets are produced in large quantities in Asia; corn and sorghum are major crops in America, and barley, oats and rye are major crops in the former USSR and Europe (Chavan and Kadam, 1989). There is evidence to suggest that regular consumption whole grains, have an important role in the avoidance of chronic diseases like coronary heart disease, diabetes and colorectal cancer. The mechanisms by which they convey beneficial effects on health are not clear exactly. It is expected that a number of factors may be involved, e.g. their micronutrient content, their fibre content and/or their glycaemic index. As there are many encouraging health effects related with consumption of wholegrain cereals, boosting their intake seems a judicious public health approach. Furthermore, a wider range of wholegrain foods that are quick and easy to prepare would help people increase their consumption of such foods. 2.4.1 Chemical composition of cereals The components of cereals are not homogeneously distributed in the grain. Hulls and bran are high in cellulose, pentosans and ash. Lipids are generally concerted in the aleurone and germ. The endosperm, contains mostly starch, has lower protein content than the germ and the bran, and is also low in fat and ash. Compositionally, cereals contain of 12-14 per cent moisture, 65-75 per cent carbohydrates, 2-6 per cent lipids and 7-12 per cent protein. Most of the cereals are relatively similar in gross composition being low in protein and high in carbohydrates. However, oats and maize comprise of relatively large amounts of lipids. Different cultivars of a given cereal show compositional variability. The proximate composition of various cereal grains is presented in Table 2.4. 16
Review of Literature Table 2.4 Proximate composition of cereal grains (percent dry weight) Cereal
Crude protein
Crude fat
Ash
Crude
Available
Fibre
Carbohydrate
Brown Rice
7.3
2.2
1.4
0.8
64.3
Sorghum
8.3
3.9
2.6
4.1
62.9
Rye
8.7
1.5
1.8
2.2
71.8
Oats
9.3
5.9
2.3
2.3
62.9
Maize
9.8
4.9
1.4
2.0
63.6
Wheat
10.6
1.9
1.4
1.0
69.7
Barley
11.0
3.4
1.9
3.7
55.8
Pearl Millet
11.5
4.7
1.5
1.5
63.4
(Alais and Linden, 1991) 2.4.2 Cereals and nutrition With the gradually changing socio-economic situation, consumers are becoming ever more health conscious and are asking for natural, wholesome and health stimulating foods. Cereals can provide different levels of fibre, protein and other nutrients, and have been reported in some cases to be involved in prevention or reduction of specific ill-health conditions. Cereals are a source of majority of the dietary protein, calories, vitamins, and minerals to the majority of populations in developing nations. People in the USA who ate whole grains had higher intakes of vitamins and minerals, and lower intakes of total fat, saturates and added sugars compared to those who did not eat whole grains (Cleaveland et al. 2000). Epidemiological studies states that foods rich in whole grains may safeguard against hypertension, stroke, cardiovascular disease, and Type II diabetes. Cereals have lower total protein content in comparison to legumes and oilseeds. Lysine is the first limiting essential amino acid for man; however, rice, oats and barley contain more lysine compared to other cereals. Tryptophan is a limiting amino acid in corn protein, while other cereals are mostly limiting in threonine. A comparative assessment of nutritive value of some cereal grains is abridged in Table 2.5.
17
Review of Literature Table 2.5 Comparative nutritive value of cereal grains Nutritive Factor
Wheat Maize
Brown Rice
Barley Sorghum
Oat
Rye 71.8
Available CHO (%)
69.7
63.6
64.3
55.8
62.9
62.9
Energy (kJ/100 g)
1570
1660
1610
1630
1610
1640 1570
Digestible energy (%)
86.4
87.2
96.3
81.0
79.9
70.6
85.0
- Thiamin
0.45
0.32
0.29
0.10
0.33
0.60
0.66
- Riboflavin
0.10
0.10
0.04
0.04
0.13
0.14
0.25
- Niacin
3.7
1.9
4.0
2.7
3.4
1.3
1.3
- Lysine
2.3
2.5
3.8
3.2
2.7
4.0
3.7
- Threonine
2.8
3.2
3.6
2.9
3.3
3.6
3.3
- Metheonine &
3.6
3.9
3.9
3.9
2.8
4.8
3.7
1.0
0.6
1.1
1.7
1.0
0.9
1.0
-True digestibility
96.0
95.0
99.7
88.0
84.8
84.1
77.0
- Biological value
55.0
61.0
74.0
70.0
59.2
70.4
77.7
Net protein utilization
53.0
58.0
73.8
62.0
50.0
59.1
59.0
Utilizable protein
5.6
5.7
5.4
6.8
4.2
5.5
5.1
Vitamins (mg/100 g)
Amino acids (g/16 g N)
Cystine - Tryptophan Protein quality (%)
(Chavan and Kadam, 1989) 2.5 RICE Rice, also called paddy rice, common rice, lowland or upland rice, is the major caloric source for a large portion of the earth’s population. Rice (Oryza sativa L) is one of the most important cereal crops for human consumption in the world (Zaupa et al., 2016). It is produced in at least 95 countries around the globe, with China producing 36 per cent of the world’s production in 1999, followed by India at 21 per cent, Indonesia at 8 per cent, and Bangladesh and Vietnam each producing about 5 per cent (Chang, 2003). The importance of rice lies in many spheres - as food, as a source of income and employment (economy), as well as in social development and culture.
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Review of Literature World rice production of the year 2013 was 740.90 MMT, of which India accounted for 21.49 per cent (FAOSTAT, 2014). Usually rice is consumed in the polished form, in which the outer layers of the caryopsis are removed. However, from the nutritional point of view, the consumption of unpolished rice is preferable, because a large amount of nutritionally relevant compounds such as fiber, proteins, vitamins and minerals are located in the bran (Fardet et al., 2008). In recent years pigmented rice varieties have received increased attention because of their antioxidant properties, related to presence of phenolic compounds mainly located in the outer layer of the caryopsis (Fardet et al, 2008; Finoccharo et al., 2010). 2.5.1 Rice Quality The different quality characteristics of the grain play a decisive role in determining the efficiency or suitability of every step of pre-processing, the palatability of the end products, and the selection of varieties, products and processing conditions for the different end uses (Bhattacharya, 2011). Besides being a staple food item, rice is used in desserts and as a breakfast cereal. Major categories of rice include: raw rice, parboiled rice (steeped, steamed and dried while still in husk). Depending on the end use, rice processing may involve any or all wide range of processing operations like cooking, flacking, roasting, puffing, extrusion, etc. (Jha, 2000). Thermal treatment can modify the structure of the matrix influencing the accessibility and probably the localization of antioxidants and other compounds (Parada and Aguilera, 2007). However, cooking or heating in presence of water is by far the most widely used process, and the only one in relation to kheer making by traditional process. Quality in rice may be categorized in to two major areas: Grain quality indicators and cooking quality indicators. 2.5.1.1 Grain quality indicators Grain quality indicators mainly include size and shape of grains along with colour and translucency of grains. A huge variation in size and shape of rice grains exists depending on genetic makeup and variety of rice (Huang et al., 2013). La Bell (1994) noted that selection of rice for various rice based desserts like rice pudding depends on taste, appearance and nutritional value. The various types of rice used for making rice pudding includes brown rice, long grain rice and medium grain rice. 19
Review of Literature Grain dimensions are expressed as length, width and thickness, while ratio of length and width is known as shape of grain. Besides its contribution to grain yield, grain shape is an important quality trait that has a major impact on the market values of rice grain products. There are there major types of rice, long, medium and short depending on grain length, and tend to have different properties and hence different uses (Ranken et al., 1997). A long, slender grain of rice is generally preferred by consumers in Southern China, the USA, and South and Southeast Asian countries, whereas consumers in Japan, Korea, and Northern China prefer a rice grain that is short and round. Grain length can be as short as 6 mm to over 15 mm (Huang et al., 2013). White and translucent rice is preferred by people all over the world. The colour of the unpolished rice or brown rice is normally pale white, creamy white, brown or reddish. Upon polishing the grain becomes white, translucent or opaque depending on type of pericarp and endosperm colour of brown rice (Lamberts et al., 2007). 2.5.1.2 Cooking quality indicators Cooking quality of rice is the primary factor of importance in the rice consuming areas. Milling, processing and cooking qualities are the fundamental components of quality that control economic value of rice. The major cooking quality parameters include amylose content, gelatinization temperature and gel consistency. Amylose content of rice is deliberated as important parameter for envisaging rice cooking and processing behaviour. The amylose content in rice varies from 15 to 37 per cent. High amylose content is linked with non-sticky cooking characteristics and vice-versa (Bhattacharya, 2011). Rice containing no or less amylose becomes very sticky on cooking, it is also known as waxy rice. The indica varieties of rice contains 25 to 30 per cent amylose, while the same for japonica type varieties is 15 to 20 per cent. High amylose containing rice is used in Indian sub-continent including India, Pakistan, Bangladesh and Sri Lanka (ICAR, 1980). The time required for cooking milled rice is determined by gelatinization temperature. Gelatinization temperature of starch is the temperature range in which the starch swells irreversibly with loss of crystallinity. It normally varies between 69° to 75°C for rice (Shelton and Lee, 2000; Mutters and Thompson, 2009). This 20
Review of Literature character in milled rice is evaluated by determining the alkali spreading value, a standard assay used to classify the processing and cooking quality of rice. Rice is classified in to high, intermediate and low gelatinization temperature types based on the extent of grain dispersion when soaked in a KOH solution (1.7 to 2.0 per cent) for 16 to 24 hours. Alkali spreading value is inversely related to the temperature at which rice starch granules gelatinize (Mutters and Thompson, 2009). Gel consistency measures the tendency of cooked rice to harden after cooling. Within a given amylose group, varieties with softer gel have a higher degree of tenderness when cooked. Harder gel consistency and firmer cooked rice are associated with high amylose. Hard cooked rice also tend to be less sticky. Among high amylose rice, intermediate gelatinization temperature and soft gel consistency are preferred by consumers over low gelatinization temperature and hard gel consistency (Kaw and Cruz, 1990). The typical Indian rice cooks as non-sticky but soft, long and medium, slender grains and has intermediate gelatinization temperature, soft gel consistency along with high amylose content (Bhattacharya, 2011). 2.6 PROCESSING OF RICE Rice is used in preparation of desserts like kheer, phirni, paysam etc.as well as in breakfast cereals, besides being a staple food in certain countries. The main categories of rice include: raw, parboiled and quick cooking rice. Rice processing involves any or all types of operations viz. cooking, flaking, roasting, puffing, extrusion etc. depending on the final use. However cooking in presence of water is the most common and relevant process in relation to kheer making. 2.6.1 Cooking/ heating of rice in presence of water Rice is cooked to make it palatable and to increase its digestibility. Cooking behaviour of rice in presence of rice is mostly dependent on properties of starch, mainly related to amylose content and gelatinization temperature. Approximately 2 to 6 volumes of water is required per volume of rice grain for cooking due to uptake of water by starch during gelatinization (Yadav and Jindal, 2007). Gelatinization of starch is the most prominent change taking place during cooking of rice. It results in water uptake by starch granules along with expansion of network of starch molecule chains. Swelling and softening of gelatinizing rice grains are related processes. The uptake of water was found to be related to the surface area 21
Review of Literature (Bhattacharya, 2011). Normally, the uptake of water per g with a fixed time of cooking was known to be high for slender varieties, due to their high surface area per g, but low for big and round varieties due to low surface area per g of rice (Stermer, 1968). Kernel expansion or volume expansion is regarded as the ratio of volume of cooked rice to that of uncooked rice. It normally ranges from 2.00 to 4.35 in most of the varieties. Variations in the extent of swelling of rice on cooking is related to its amylose content. Similarly, grain elongation is also related with cooking of rice (Govindaswami and Ghosh, 1970). If the rice water mixture is agitated during cooking, many starch granules dislocates from grains. It thicken the liquid around the individual rice particles, thus giving a cooked rice with individual grains surrounded in a thick starch paste, when water is not much excess of grains (Ott, 1987). Further, during the cooking process, water is assumed to disturb the protein matrix and part of the protein bodies as well as starch granules (Jha, 2000). 2.6.2 Effect of soaking Generally soaking is done prior to cooking of rice. It is the process of holding the rice grains covered in water for definite time period. The major effect of soaking is water uptake by rice grains. It has been reported that the cooked rice quality may also be influenced by pre-soaking. Okuno and Adachi (1992) found that pre-soaking of milled rice in water was important to have cooked rice of good sensory quality. Improved cooking rate is an important benefit of pre-soaking of rice (Desikachar and Subrahmanyam, 1960). Pre-soaking of rice considerably decreases the energy required for cooking (Gunasekara and Dharmasena, 2011). 2.6.3 Properties of cooked rice Acceptability of cooked rice mainly depends on the texture of the grains (Meullenet et al., 2000). Some consumers prefer long grain, soft or slightly dry and separate kernels, with typical cooked rice flavour. In contrast, in China and Japan short grain, somewhat pasty and sticky cooked rice is preferred (Deshpande and Bhattacharya, 1982). Upon storage the rice gradually becomes drier on cooking particularly the short grain type. Therefore, to have pastiness which is preferred by 22
Review of Literature Japanese, waxy rice is added in small amounts to increase pastiness of stored rice (Jha et al, 2002). Retrogradation is also an important property of starch. It refers to rearrangement or re-association of amylose during storage (Ott, 1987). Such rearrangement in the system containing colloidal dispersion of amylose leads to gel formation during cooling of gelatinized starch (Tako et al., 2014). Bhattacharya et al. (1978) reported that the textural properties of cooked rice were not entirely dependent on total amylose but on insoluble amylose content. More recent studies suggested that the long β chains of amylopectin, which were strongly positively correlated with the insoluble amylose content, were the key determinant of rice texture (Cameron and Wang, 2005). 2.7 QUICK COOKING RICE Quick cooking rice or instant rice are precooked and gelatinized to some extent in water or steam or combination of both (Dutta and Mahanta, 2014). Quick cooking rice have applications in dry soup mixes, puddings, flavoured free flowing rice and in prepared dry mixes. They were also part of menu of US space shuttle orbiter (Bourland et al., 1981). The cooked or partially cooked rice is usually dried in such a way that they retain porous structure. The finished product generally consists of dry, individual grains, mostly free from lumps and approximately 1.5 to 3.0 x the volume of raw rice grains. The boiling water used in final preparation of product should penetrate the product in relatively short time (Smith et al. 1985; Luh, 2013). Many quick cooking rice products, having difference in texture, appearance, taste etc. are designed for certain specific uses depending on rehydration time and similar other requirements. 2.7.1 Methods of manufacture of quick cooking rice Several methods of manufacture of quick cooking rice and rice products have been developed. Many approaches and numerous equipment design modifications have been tried. Some of the commercially viable processes and products developed in past have been reviewed by Roberts (1952, 1972), Juliano and Sakurai (1985) and Jha (2000).
23
Review of Literature Ozai-Durrani (1948) method used by General Foods to make ‘Minute Rice’ consisted of soaking milled rice in water at room temperature, cooking in boiling water (65-70 per cent moisture), draining, cooling, washing in cold water and drying with forced air at 140°C (14 per cent moisture). Long and medium grain rice has been in common use for manufacture of quick cooking rice. Short grain varieties have problem of handling and removal of water after cooking due to lump formation. Quixiang (2011) reported a method of fast cooking rice for use in pudding, jellies, rice cake etc. Rice is added to hot water at 75°C and steamed for 45 s and rapidly cooled to 15°C to avoid starch retrogradation. The excess water is then drained and the product is dried in blast oven with outlet temperature not less than 80°C with air velocity of 5 m/sec. The dried product then packed. The quick cooked rice is then converted in to powder and can be used for making products like pudding, porridge etc. Linn et al. (2009) used microwave heating of packed rice in a tunnel at 130°C for production of quick cooking rice. In another study the application of high hydrostatic pressure was used in combination with microwave processing for manufacture of quick cooking rice. Two stage high hydrostatic pressure was applied at 400 and 570 MPa for 4 and 20 min respectively. The treated rice was then heated in microwave for 1.5 min. The resultant quick cooking rice had better sensory quality than quick cooking rice made using only microwave for 10.0 min (Aguilara et al., 2013). Carlson et al. (1976) described a process suitable for all varieties of rice which involved the use of a centrifugal fluidized bed for low temperature short time drying of quick cooking rice. Cheevitsopon and Noomhorm (2015) used fluidized bed dryer for drying of parboiled brown rice. Homogeneous fluidization ensures equal exposure of air stream to all the particles, which helps in elimination of heat damage and scorched particles (Jaiboon et al., 2011). Baz et al. (1992) developed a process for quick cooking rice in which rice was initially cooked at 90 – 100°C for 1–10 min, subsequently pressure cooked in water and dried at 140 – 205°C. Ghosh and Mukherjee (1988) obtained dried quick cooking rice, by cooking parboiled rice in boiling water for 25 min, or steaming for 10 min at 1.1 kg/cm2 followed by tray drying. However, the product obtained was inferior in quality due to atmospheric tray drying. 24
Review of Literature 2.8 CONVENIENCE FOODS India being one of the largest food producers in the world is slated to become a global outsourcing hub for production of convenience foods. Therefore, in India the food processing is identified as Sun-rise Industry. The de-regulation and liberalization of Indian economy has boosted the food processing Industry which is mainly engaged in production of convenience foods and therefore more and more industries are venturing into the food industry. Today, more than 30 companies (including few MNCs) are processing and marketing convenience foods in the country (Vaghela, 2015). Convenience foods as defined by Henry (1993) are “Foods that have undergone major processing by the manufacturer such that they require little or no secondary processing/cooking before consumption” this means apart from warming, thawing, cooking, frying, diluting and reconstitution the food is ready-to-eat (RTE). According to Premavalli (2000) convenience foods are a class of foods which impart ease to the consumers in terms of handling by way of little or no requirements of major processing or cooking before their consumption. Convenience foods require a minimum handling, like mild heating / warming for RTE products or rehydration in hot/cold water for dehydrated foods. In addition to meeting defence supplies, the additional convenience for long shelf life, reduction in weight, good quality and easy availability are of major concern. The intricacy of convenience foods lies in their composition, shape, size and method of processing. Viewing this heterogeneity, conversion of the product into a simpler form with minimum handling prior to consumption involves the skill of the technologist. The major thrust is to provide convenience by way of saving the cooking time and labour in the kitchen. Traditional sweets form a major chunk of convenience foods. With the improved economy, superior purchasing power and better standard of living, market for prepared foods and sweets also increased. In the present situation of relatively better economy and good purchasing power, consumers are not willing and they don’t have time to spend in the preparation of sweets or desserts at home. This is the reason that numerous dry mixes of foods including spice mixes have been invented and available in the market. According to the market trend, consumers appear to have 25
Review of Literature willingly welcomed them. It also appears that dry mix of any food is acceptable to consumers as long as it yields acceptable quality product with most of the quality attributes intact, if not all (Rangarao et. al, 2004). For some foods it is easy to formulate a dry mix, but for some others, it is a bit complex and ingredient proportions and processing parameters have to be carefully optimized. Convenience foods can be broadly classified into three groups, viz., RTE foods, ready- to-reconstitute (RTR) foods and ready-to-serve (RTS) beverages. 2.8.1 Ready-To-Eat (RTE) Foods Over the time, with the knowledge of traditional foods background, many of the foods have been converted into convenience form of processed food under readyto-eat foods. The shelf stable foods are canned foods with shelf life of one year. The various processing methods involved for these foods are canning, frying, concentration, baking, puffing, extrusion, retorting, dehydration, incorporation preservatives and fermentation. The shelf life deviation is based on the type of processing used and the packaging employed. Quality deterioration reactions during storage of preserved foods occur based on the composition of the food. The commercialized products are canned products (kheer, curry, halwa), retort processed food products (biryani, halwa, aloo choley), baked / steamed products (chapaties, puris, dosa), puffed products, extruded products, fruit and vegetable based products (jam, pickels, murabbas), etc. A lot of scope exists for future growth in the preservation of many food products with a long shelf life (Premavalli, 2000). 2.8.2 Ready-To-Reconstitute (RTR) Foods Ready-to-reconstitute foods are normally available in dry form and need to be mixed with water before consumption. But, sometimes needs very little cooking also. Instant mixes are the major players in this category which require reconstitution in boiling water with simmering for 2-10 min, depending on the type of processing and the composition of the food. In general, these are precooked and dehydrated foods which need rehydration later to bring them into consumable form. However, keeping in view the sensory characteristics of some foods, such as textural attributes of dhal, rice, vegetables; flavour attributes of spices; colour constituents’ retention during processing and 26
Review of Literature decrease of cooking time prior to consumption, the preservative(s) treatment and method of dehydration is adopted. The selection of appropriate processing method itself is an art clubbed with scientific background. This group of foods needs a little more cooking in terms of baking of cake mix, frying in oil / ghee and dipping in sugar syrup in case of gulabjamun mix, steaming in relation to idli, dosa, dhokla mix, noodles, and incorporation of milk and flavours in to breakfast cereals. The commercialization of these types of food products is increasing but at a slower rate. A few of such products, like gulabjamun mix, rava idli mix, noodles, breakfast cereals and fruit products are accepted well but the staple cereal-based products necessitate a diverse marketing strategy. This is because the consumers may psychologically not realise the convenience in terms of savings of labour, materials, cooking utensils and are financially not willing or not in a position to compromise the cost to convenience ratio. The technologies for most of the instant mixes are available. A few products, such as halwa mix, upma mix, bisibele bhath mix, pulav mix, khichidi mix, kheer mix, dalia mix and spiced dhal mix are manufactured commercially, but generally when we talk about milk cereal based dessert ready mixes, they lack the sensory quality acquired by traditional method of preparation (Premavalli, 2000). The major groups include:
Instant Dry Mixes - to be heated with boiling water - Bisibele bhath mix, Pulav mix, Khichidi mix, Choley mix, Sambhar mix, Rasam mix, Upma mix, Spiced dhal mix, Spiced green leaves - rice mix, Avial mix, Tam-rice mix, Urad rice mix, Chutney mix, Lemon rice mix, Halwa mix, Basundi mix etc.
Instant Dry Mixes - to be fried, baked or cooked - Gulabjamun mix, Cake mix, Dosa mix, ldli mix, Rava ldli mix, Noodles, Breakfast cereals, Kheer mix, Dalia mix, Payasam mix etc.
Fruit products – Squashes, Cordials, Nectars, Fruit juice concentrates, Fruit powders, etc. (Alexander et al., 2011).
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Review of Literature 2.8.3 Ready to serve foods (RTS)/ Ready to use foods (RTU) The ready-to-use (RTU) foods meet the needs of urgent situations as well as saving of time for preparation. Several traditional foods are available in RTU form presenting convenience to the consumer. These include: desserts / sweet (custard powder, payasam, kheer mix, carrot halwa mix etc); Breakfast / snacks (vada, dhokla, dosa, utappam, idli, upma, etc); Beverages (badam drinks, soups etc). Several milk based dry mixes such as gulabjamun mix, kulfi mix, rasmalai mix, rabri mix, basundi mix, milk shake mix etc. are available in the market. The benefits of dry mixes are that the final product can be prepared easily, and it saves the time. The product made from dry mixes is of acceptable quality and the mixes have long shelf life at ambient temperature (Thote et al., 2016). 2.9 MILK BASED CONVENIENCE FOODS Milk based convenience foods are having limited availability in market. Considering milk as a perishable commodity, there is a large scope of instant mixes made out of milk to be converted in to actual product with very less cooking before consumption. Dried products requires less packaging, storage and distribution cost, because of reduction of bulk water and eradication of refrigeration for storage and transport.
India is located amidst milk deficit countries in Asia. Lower cost of
production and more availability of milk in India, there is a very good chance of export of milk based convenience products to the neighbouring countries as they also have similar traditional products, but don’t have technology to produce it at large scale and extending the shelf life (Thote et al., 2016). The work related to development of milk based convenience foods is summarized in this section. 2.9.1 Instant Kheer Mix Jha et al., (2002) optimized a process for manufacture of instant kheer mix (IKM). The process involved standardization of buffalo milk followed by vacuum concentration, addition of ground rice flour and part sugar, pre-heating the slurry for gelatinization of starch and finally spray-bed drying by employing inlet air temperature 170°C/out let temperature 86°C and inlet air temperature 88°C/outlet temperature 80°C respectively for spray dryer and fluidized bed dryer. The powder so obtained was dry blended with ground sugar to obtain instant kheer mix. The freshly prepared powder had a good flowability (angle of repose, 40.09°) and fairly high 28
Review of Literature loose and packed bulk densities (0.69 g/cm3 and 0.81 g/cm3, respectively) corresponding to a particle density of 1.25 g/cm3, occluded air content of 6.63 cm3/100 g, interstitial air content of 45.00 cm3/100 g and porosity of 44.80 per cent. It showed an insolubility index of 4.00 ml, wettability of 2.00 min, and dispersibility of 75.38 per cent. Jha (2000) illustrated that the colour score of reconstituted kheer made from IKM powder decreased from 8.75 to 7.9 and 7.5 after storage using a 9 point hedonic scale. The flavor score declined significantly (P50
Desirable Attributes: Kheer is having white to creamish yellow colour. It is thick bodied and homogeneous mass of milk and rice. It is characterized by a sweet, nutty and pleasant flavour. The given samples are evaluated for their sensory quality using the following rating scale: Hedonic Rating Like extremely Like very much Like moderately Like Slightly Neither like nor dislike Dislike Slightly Dislike moderately Dislike very much Dislike extremely
Score 9 8 7 6 5 4 3 2 1
Evaluate the given samples using above guidelines Sensory Attributes
A
Colour & Appearance Consistency Flavour Package Overall Acceptability
Comments: (If any) Signature
vii
B
