Indira Gandhi BPVI-015 National Open University School of Agriculture Dairy Products-II

Block 1 HEAT DESICCATED PRODUCTS UNIT 1

Definition, Composition and Standards of Khoa, Rabri and Basundi 5 UNIT 2

Methods of Manufacture and Factors Affecting Quality of Products 18

UNIT 3

Khoa Based Sweets 34

UNIT 4

Packaging, Shelf Life and Storage of Khoa and Khoa Based Sweets 51 Programme Design Committee

Prof. H.P. Dikshit Prof. Panjab Singh Ex. Vice Chancellor Vice Chancellor IGNOU, New Delhi Banaras Hindu University, Banaras (U.P.) Prof. S.C. Garg, Shri A.N.P. Sinha Acting Vice Chancellor Former Additional Secretary IGNOU, New Delhi Ministry of Food Processing Industries Delhi

Ministry of Food Processing Industries Milk Plant, Gwalior: New Delhi : Shri M.E. Khan, Manager - Plant Operation • Mr. K.K. Maheshwary • Mr. R.K. Bansal, Consultant Delhi Milk Scheme, Delhi: • Mr. V.K. Dahiya, Tech. Officer Shri Ashok Bansal, DGM (Milk Products) CITA, New Delhi: NDRI, Karnal, Haryana: Shri Vijay Sardana • Dr. S. Singh, JD (Academics) • Dr. S.P. Agrawala, Head (Dairy Engg.) Mahaan Protein, Mathura (U.P.): • Dr. Rajvir Singh, Head (Dairy Eco.) Dr. Ashwani Kumar Rathor, GM Technical • Dr. K.L. Bhatia, Ex-Principal Scientist • Dr. S.K. Tomar, Principal Scientist IGNOU, New Delhi (SOA Faculty Members): • Dr. B.D. Tiwari, Ex. Principal Scientist • Dr. M.K. Salooja, Dy. Director • Dr. Dharam Pal, Principal Scientist • Dr. M.C. Nair, Dy. Director • Dr. A.A. Patel, Principal Scientist • Dr. Indrani Lahiri, Asstt. Director • Dr. P.L. Yadav, Sr. Consultant Mother Dairy, Delhi: • Dr. D.S. Khurdiya, Sr. Consultant Dr. P.N. Reddy • Sh. Jaya Raj, Sr. Consultant Former Quality Control Manager • Sh. Rajesh Singh, Consultant Programme Coordinators : Prof. Panjab Singh, Dr. M.K. Salooja and Dr. P.L. Yadav Block Preparation Team Writer Course Coordinator Dr. Dharam Pal Dr. M.K. Salooja Editors Dr. P.L. Yadav Dr. P.L. Yadav Dr. J.S. Sandhu Dr. J.S. Sindhu Dr. M.K. Salooja Material Production Mr. Rajiv Girdhar, SO (Publication) Secretarial Assistance Mr. Vinay Sehgal

Word Processing Mr. Bhim Singh

October, 2006 © Indira Gandhi National Open University, 2006 ISBN-81-266-2588-0 All rights reserved. No part of this work may be reproduced in any form, by mimeograph or any other means, without permission in writing from the Indira Gandhi National Open University. Further information on Indira Gandhi National Open University courses may be obtained from the University's office at Maidan Garhi, New Delhi-110 068. Printed and published on behalf of the Indira Gandhi National Open University, New Delhi by Director, School of Agriculture Paper Used : Agrobased Environment Friendly Lasertypesetted at Graphic Printers, 204, Pankaj Tower, Mayur Vihar, Phase-I, Delhi-91. Printet at : BLOCK INTRODUCTION

Indigenous dairy products are made throughout the country. Converting milk into indigenous milk products is essential to preserve surplus milk in remote area of country. Milk produced in villages is mostly converted into khoa in certain part of country like north and west India. A number of sweets made from khoa are very popular. In this block we shall know about the manufacture of khoa, khoa based sweets and packaging of the khoa based sweets. Unit-1 We will learn about the classification of traditional dairy products made in our country. Standards of khoa, Rabri and Basundi prescribed under law also will be known to us. Different factors responsible for affecting the quality of khoa, Rabri and Basundi are explained in this unit so that while making these products we can take care of these factors. Nutritive Values of these products are given in this unit. We will also learn about the physico-chemical changes taking place during manufacture of Khoa, Rabri and Basundi. Unit-2 Methods of manufacture and factor affecting quality of products are given in this unit. We will learn about the principle of manufacture. Traditional method and improved method of manufacture of khoa, Rabri and Basundi are explained in the text of this unit. Unit-3 In our country milk sweets are very popular. In this unit we will know about the method of manufacture and standards of khoa based sweets like Burfi, , Gulabjamun, Kalajamun, Kalakand, Milk cake and Kunda. Unit-4 Suitable packaging for better keeping quality and proper storage are most important for khoa and khoa based sweets for commercial purposes. In this unit we will learn about the packaging and factors affecting shelf life of khoa, Rabri and Basundi. We will also understand about the storage and defects of khoa and khoa based sweets in this unit. COURSE INTRODUCTION

A number of products are manufactured from milk. In India Khoa, Paneer and Chhana, concentrated milk and milk powder are manufactured from surplus milk. Khoa, Paneer and Chhana are traditional product which are produced in very small quantity by small dealers or consumers themselves. With the development of new Technology is possible to utilized surplus milk during flush season of year for making Paneer, Chhana and Khoa, on large scale. Khoa, and Chhana are used for preparation of a variety of sweets dishes in our country by small manufactures. These sweets are very common throught the country. Milk production in our country has increased many fold since independence. A number of milk processing and milk products manufacturing plants are utilizing large quantity of surplus milk available for production of concentrated milk and Milk Powders. These products can be stored for longer period and utilized during the period of lean season. Milk powder has great commercial value and used to meet the demand of milk and milk products in deficit areas of country. In this course we will study about the manufacture of heat- desiccated products specially khoa, and khoa sweets, Paneer and Chhana, concentrated milk and dried milk. Block-1 We will learn about the manufacturing of Khoa, Rabri and Basundi in this block. We will know the principle involved in manufacture of these products. Composition, standards and classification of heat-desiccated product are also given in the text of this block. There are a numbers of sweets made from khoa like Gulabjamun, Peda, Burfi, Kalakand and milk cake. We will learn about the preparation, packaging, storage and common defects of the products. This will help us to take care in preparation and handling of the products for subsequent use. Block-2 Paneer and Chhana are heat and acid coagulated products made from milk. In this block we will learn about the composition, standard, factor affecting quality, methods of manufacture packaging and storage also of the products. We will also learn about the preparation of Chhana based sweets like Rasogulla, Sandesh, Rasmalai, Chhana Murki etc. Microbiological quality of Paneer, Chhana, and Chhana based sweets, common defects in these products and their preservation are also given in the text of this block. Block-3 Milk constituents in a concentrated form are preserved in the form of concentrated milk or condensed milk with or without sugar. Concentrated milk can be easily reconstituted to meet the fluid milk demand in scarcity period. In this block we will learn about the definition, standard, nutritive value and principle of evaporation for concentrated milk. Method of manufacture of sweetened condensed and evaporated milk and their uses are also given in the block. We will also learn about the packaging, storage, judging and grading of the products. Condensed milk and evaporated milk have prolonged storage life, but sometime some defects develop, the reason for occurance and measure to control these defects shall also be discussed in this block. Block-4 Milk powder has many beneficial use in the milk and food industry. It can be stored for longer period and can be easily transported to long distance without deterioration. In this block we will study about the definition, compositions, classification, legal standard and principle of drying milk. Milk is dried by roller drier, spray drier, fluid bed drier. We will know about the engineering aspects of these driers. In this block methods of manufacture of spray and roller dried milk and production of value added products are given to educate us about the preparation of products. We will also learn about the packaging, storage, and common defects of dried milk, which will help us in maintaining the quality of dried milk. UNIT 1 DEFINITION, COMPOSITION AND STANDARDS OF KHOA, RABRI AND BASUNDI

Structure 1.0 Objectives 1.1 Introduction 1.2 Classification of Traditional Dairy Products 1.3 Khoa • Standards • Chemical composition of khoa • Factors affecting composition of khoa 1.4 Rabri • Definition • Chemical composition of rabri • Factors affecting composition of rabri 1.5 Basundi • Definition 1.6 Nutritive Value of Heat Desiccated Dairy Products 1.7 Physico-chemical Changes During Heat Desiccation of Milk 1.8 Let Us Sum Up 1.9 Key Words 1.10 Some Useful Books 1.11 Answers to Check Your Progress Exercises 1.0 OBJECTIVES

After reading this unit we should be able to: • state the significance of traditional Indian dairy products. • classify traditional dairy products on the basis of principle of their manufacture. • give the definitions, standards and composition of khoa, rabri and basundi. • correlate different inherent and processing factors with the composition of khoa, rabri and basundi. • narrate the physico-chemical changes that take place in milk during manufacture of these products. 1.1 INTRODUCTION

These products are being made and consumed in India since ancient time. Traditional milk products, also called as “Indian” or “Indigenous” milk products have great 5 Heat Desiccated Products social, cultural and economic importance in our country. It is estimated that about half of the 88 million tons (figures based on 2004 estimates) of milk produced in India is utilized for the manufacture of traditional milk products. Indigenous milk products provide the means of preserving precious milk solids for a comparatively longer time than the fluid milk whose shelf life under Indian tropical conditions is only 5-6 hours at ambient temperature. The chilling facilities for preserving raw milk are highly inadequate and legally no chemical preservative can be added to milk for this purpose. In this situation conversion of milk into traditional milk products is the best option, because methods of preparation are simple, don’t require costly equipment and suits the rural conditions. Until recently the surplus milk in flush season was converted into skim milk powder and ghee by most of the organized dairies, mainly because of their convenience in handling, transportation and storage. Because of increase in competition and decrease of profit in these products, the organized sector of dairy industry is fast switching to value added products such as traditional milk sweets. Traditional milk products are now finding good export opportunity. We can conclude that traditional have great role in both unorganized (halwais) and organized dairy/milk processing sectors. 1.2 CLASSIFICATION OF TRADITIONAL DAIRY PRODUCTS

Innumerable types of traditional dairy products are prepared in our country (Table 1.1). Some of them have attained national status while many others are still very region specific. The type of a indigenous dairy product popular in an area/region chiefly depends on the following factors. • Quantity of milk available • Dietary habit of the people • Market demand • Purchasing power of the consumers • Religious and ceremonial occasions • Profitability • Shelf life • Other local conditions, such as facilities available, seasonal ban on product manufacture, etc. Table 1.1 Classification of traditional milk products

Principle of Primary/ End products manufacture Intermediate products Heat desiccation Khoa Khoa based sweets (Burfi, peda Gulabjamun, Kalakand, Milk cake, Kunda, etc). - Rabri - Basundi

6 Heat and acid Chhana Chhana based sweets Definition, Composition and coagulation (Rasogolla, Sandesh, Standards of Khoa, Rasmalai, Chhana murki, Rabri and Basundi Cham-cham, etc.) Paneer Culinary dishes/direct consumption Fermentation - Dahi Chakka Shrikhand, Shrikhand vadi - Misti doi Phase inversion and Makkhan Ghee concentration of fat Frozen - / Kulfa Cereal based - Kheer - Payasam

Check Your Progress - 1 1) What do you understand by traditional Indian dairy products? Of the total milk production, how much is converted into dairy products? ...... 2) State the major benefits of manufacturing traditional dairy products...... 3) Classify traditional dairy products on the basis of their principle of manufacture...... 1.3 KHOA

Khoa is an important indigenous milk product. It is conventionally prepared by continuous boiling of milk in an open kettle until desired desiccation (normally 72- 75% total solids) and texture is achieved. According to one estimate about 5.5% of total milk production is converted into khoa. This amount is equivalent to 3 million kgs khoa/per day. Khoa is used as a base material for a variety of sweets, such as burfi, peda, gulabjamum, milk cake, kalakand, kunda etc. i. Standard PFA Standards of Khoa : According to PFA khoa is a product obtained from cow or buffalo milk or a combination thereof by rapid desiccation and having not less than 30% fat on dry matter basis of the finished product. BIS requirements for Different Types of Khoa : According to BIS, khoa is a heat coagulated milk product obtained by partial dehydration of milk of buffalo, cow, sheep and goat or their admixture. It shall not contain any ingredient foreign to milk except the addition of citric acid in Danedar khoa added to develop the desirable 7 Heat Desiccated Products characteristic. Three types of khoa are manufactured, viz. Pindi, Danedar and Dhap. Their requirements as per BIS are given in table 1.2 and specific characteristics as below: Pindi: It is characterized as a circular ball of a hemispherical pat with smooth and homogenous body and texture. The grains are very small and of uniform size throughout the mass. The product possesses characteristic heated/cooked flavour. It is used for the manufacture of various varieties of burfi and peda. Danedar: It is characterized by its granular texture and uneven body. The size of grains depends upon the amount of acidulant added and the acidity of milk used. Citric acid when added should normally be less than 0.1% (preferably 0.02%). This type of khoa is used as a base for the preparation of kalakand, milk cake and pastries where granulation is desirable. Dhap: This type is characterized by loose and sticky body and smooth texture. It is normally pre-pindi stage and thus contains higher moisture. Dhap khoa is purposely prepared for its use in preparation of gulabjamun and so that balls of smooth surface can be prepared. Table 1.2. BIS requirements for different types of khoa

Sl.No. Characteristics Requirements Pindi Danedar Dhap 1. Total solids, % by mass, min 65 60 55 2. Fat, % by mass (on dry basis), min 37 37 37 3. Total ash, % by mass (on dry basis, max 6.0 6.0 6.0 4. Titratable acidity (as lactic acid), % by 0.8 0.9 0.6 mass, max. 5. Colifom count/g, max 90 90 90 6. Yeast & mould counts/g, max 50 50 50 End uses Burfi, Kalakand Gulabjamun Peda milk cakes Pantua ii. Chemical Composition of Khoa The composition of market samples of khoa shows great variation. The main reason for this variation is that manufacture of khoa is largely in the hands of private traders (halwais) who do not adopt standard practices for khoa making. The composition of khoa has been given in table 1.3. Table 1.3. Gross chemical composition of khoa Market Laboratory prepared Laboratory Constituents samples khoa from Buffalo prepared khoa (%) (range) milk* from cow milk** Moisture 20 – 40 32.0 30.4 Fat 22 – 39 24.2 22.2 Protein 16 – 26 18.3 18.8 Lactose 17 – 33 22.0 24.9 Ash 3 – 5 3.5 3.7

* Khoa prepared from standardized buffalo milk (5.8% fat and 9% SNF) under controlled conditions.

8 ** Khoa prepared from cow milk standardized to 4.0% fat and 8.6% SNF iii. Factors Affecting Composition of Khoa Definition, Composition and The large variations in the market samples are attributed to the following factors: Standards of Khoa, Rabri and Basundi Type and quality of milk used: The composition of cow and buffalo milks is different in respect of total solids, fat, proteins and lactose. Therefore, the use of these milks as such or their combination (without standardization) produces khoa of different composition. Buffalo milk khoa normally contains higher moisture and higher fat levels, but lower contents of protein, lactose and ash than cow milk khoa. Adulteration of milk with water or removal of fat from milk also affects the composition of khoa. Method of preparation: In the conventional methods, adopted by halwais and unskilled workers, the desiccation of milk is done just by their past experience, which is bound to vary from lot to lot. Removal of more moisture during desiccation leads to decrease in moisture and increase in all other solids in khoa where as the removal of less moisture has opposite effect on the composition of khoa. The use of mechanized and continuous method produces khoa of more consistent quality. Degree of heat treatment: Higher degree of heat treatment, results into very fast desiccation of milk solids particularly at the final stage. This may reduce the moisture content to a greater extent and increase all other milk solids in khoa. Manner of handling and packaging: Leaving khoa on the hot surface of heating kettle for a longer time in the conventional method of preparation or in the open trays in continuous khoa making process, causes more evaporation of moisture thereby changing its final composition. Improper protection/package of khoa also leads to surface drying and decrease in the moisture content. Storage conditions: Storage of khoa in dry conditions or humid conditions, particularly when improperly protected, also results into compositional changes. The storage of khoa for longer time will have more drastic effect in these conditions. 1.4 RABRI i. Definition Rabri is an indigenous sweetened desiccated milk product containing distinctive hard layers (flakes) of malai (clotted cream). The product also contains some liquid portion along with the layers of malai and lumpy (semi-solid) mass. Rabri has slightly cooked aroma and pleasantly sweet and creamy taste. The colour varies from light yellow to white with slight tinge of browning depending on the type of milk used. Many additives such as , dry fruits (Kaju, Badaam, etc.) are also added to rabri to make it more delicious. Rabri is very popular in the northern and eastern regions of India and consumed directly as a milk on festivals and happy occasions like marriages, birthday celebrations, etc. Standards for rabri: Neither PFA nor BIS has recommended any standard for Rabri. ii. Chemical Composition of Rabri Rabri is traditionally prepared by halwais. The method used by them is essentially a batch type based on their past experience. Therefore, large variation in the market rabri is expected. The average composition of rabri prepared in laboratory using a standard method and of the market samples (range) is given in table 1.4.

9 Heat Desiccated Products Table 1.4. Gross chemical composition of Rabri

S.No. Market Laboratory prepared Constituents samples (range) samples (average) (%) 1 Moisture 45.0 – 59.30 49.8 2 Fat 10.0 – 19.80 15.5 3 Protein - 9.5 4 Lactose 10.15 – 13.70 11.3 5 Sucrose 10.50 – 14.00 12.0 6 Ash - 1.99

- Data not available iii. Factors Affecting Composition of Rabri Like khoa, rabri is also a heat desiccated milk product but it is sweetened by adding sugar to it after desiccation. The total solids in rabri are less, which means it is not as solid as khoa. Most of the factors that affect the composition of khoa such as type and quality of milk, degree of concentration, manner of handling and packaging, storage conditions, etc. also hold true for rabri. The additional factors that affect the composition of rabri are given as below: Level of sugar addition: Sugar is added to rabri at different levels. Addition of sugar at higher rate lowers all other milk constituents, viz. fat, protein, lactose and ash contents in rabri, whereas lower sugar rate will have opposite effect on the composition of rabri. Addition of additives: The effect of additives, when added in substantial amounts, will be similar to that of sugar i.e. decrease in the percentage of all other constituents of rabri. 1.5 BASUNDI

i. Definition Basundi is a popular product of western and southern parts of India particularly states of Andhra Pradesh, Gujarat, Karnataka, Maharashtra, Kerala and Tamilnadu. The exact origin of basundi is not known, but it has been consumed as a milk dessert in our country for centuries. It is served during special festivities and religious occasions. Its production is mainly confined to the restaurants, hotels and individual household who adopt small scale batch method. Basundi is also a heat desiccated, sweetened milk like rabri. The difference between the two is based on the texture. Rabri has very distinct hard flaky layers of clotted cream (malai) whereas basundi is generally homogenous or have very soft and fine flakes, which in fact are very fine heat coagulated proteins particles. Basundi has a sweetish cooked to caramelized flavour and its colour varies from white to slight brown. Standards: So far no PFA and BIS standards exist for basundi.

10 ii. Composition of Basundi Definition, Composition and The chemical composition of Basundi depends on the Standards of Khoa, Rabri and Basundi z Type and composition of milk z Degree of concentration of milk solids z Quantity of sugar and other additives added. The average chemical composition of basundi is given below in table 1.5. Table 1.5. Average chemical composition of basundi

S.No. Constituents (%) Averages values

1 Moisture 52.6 2 Fat 11.6 3 Protein 9.9 4 Lactose 11.5 5 Ash 1.7 6 Sucrose 12.7

* Basundi prepared in the laboratory Check Your Progress - 2 1) Define khoa as per the PFA rules. How much khoa is produced per day in India? Name the main sweets made from khoa...... 2) Name the types of khoa marketed in India. Write their characteristics along with uses...... 3) Write the average composition of buffalo khoa. What are the factors that affect chemical composition of khoa...... 4) What is clotted cream? What is its role in rabri? Write a main difference between rabri and basundi? ...... 11 Heat Desiccated Products 1.6 NUTRITIVE VALUES OF HEAT DESICCATED TRADITIONAL MILK PRODUCTS

Khoa, rabri and basundi are concentrated forms of milk solids. In case of khoa, sugar is not present, but in rabri and basundi sugar is added to sweeten the products for direct consumption. So, these products are rich source of energy. Pindi khoa provides about 400 kcal/100g. The values for other types of khoa, i.e. Dhap and Danedar are slightly lower. Rabri and basundi supply about 280 and 250 kcal/100 gm products, respectively. These desiccated products are also rich source of minerals, particularly the calcium. However, some losses of milk nutrients during heat desiccation may also take place. For example, about 2.6% reduction in available lysine due to interaction between amino acid group of lysine and aldehydes group of lactose (Maillard browning) take place under drastic heat treatment in khoa. In addition, about 20-25% water-soluble vitamins are also lost during khoa making. 1.7 PHYSICO CHEMICAL CHANGES DURING MANUFACTURE OF KHOA, RABRI AND BASUNDI

i. Changes During Khoa Making Preparation of khoa involves three actions viz. heating, concentration and vigorous stirring and scraping. These actions cause following physico-chemical changes:

• The removal of moisture from milk results into concentration of milk solids and changes in their status, particularly proteins and minerals. These eventually change the state of milk from liquid to solid or semi solid. All the constituents, including lactic acid, increase in proportion to the degree of concentration.

• Denaturation of whey proteins, particularly the β-Lactoglobulin and α- Lactalbumin tend to undergo varying degree of self aggregation, denaturation/ coagulation as the temperature of milk rises above 77oC (90oC in case of buffalo milk) and their interaction start with k-casein as the heating temperature rises.

• The denaturation of the whey proteins results into production of sulfhydryl compounds, which produces characteristic cooked flavour in khoa and other heat desiccated products.

• Though casein is quite stable at high temperature, but the combined effect of severe heat treatment and concentration and complexing of whey proteins with it, substantially increases the size of casein micelles. This results into loss of stability of casein micelles. The coagulation of casein tends to increase logarithmically at a constant temperature of heating with milk solids concentration.

• Coagulation of casein and aggregation of whey proteins with it entrap part of the fat in this aggregate. The moisture also disperses as fine droplets in the aggregates of proteins.

• Vigorous agitation of milk at elevated temperatures during desiccation of milk disrupts the fat globule membrane releasing some fat in form of free fat (about 50% of the total fat). Formation of this free fat is very important from the flavour and texture point of view. 12 • The heating of milk at high temperature causes conversion of soluble calcium Definition, Composition and and magnesium to insoluble form that leads to interaction (denaturation and Standards of Khoa, hydrolytic cleavage) between protein components. Rabri and Basundi • Continuous heating of milk solids at high temperature (around boiling) causes browning. This is attributed to formation of Melanoidin pigment. This browning reaction is Maillard type due to interaction between addehyde group of lactose and free amino group of casein. ii. Changes During Rabri Making • Rabri is not a homogenous product. Part of it is in concentrated liquid form and part in form of solid and flaky material. • Most of the fat is present in form of flakes. The flakes are obtained by heat coagulation of proteins on the liquid air interface and its interaction with milk lipids (malai). • Denaturation and complexing of whey proteins with casein also result due to heating and concentration of milk but to lesser degree than in khoa. • All other changes viz. browning, lactose and mineral status and vitamin loss are similar to that in khoa. iii. Changes During Basundi Making • Unlike khoa and rabri, basundi is in concentrated liquid form (i.e. flowable product). • The rate of browning is more than khoa because sugar is added to milk during boiling and the rate of Maillard reaction is more. Some caramelization also takes place. • Denaturation of whey protein and their complexing with k-casein also take place during basundi making. But heat coagulation of casein does not appear appreciably. • Fat is present in its native state (dispersed in aqueous phase in the form fat globules), though some free fat releases due to vigorous action of stirring and scraping. Check Your Progress - 3 1) State the nutritive value of khoa, rabri and basundi and explain reasen for higher nutritive value of khoa than rabri and basundi? ...... 2) Describe the changes take place in milk proteins during manufacture of khoa? ...... 3) In which form the lipids, sugar and minerals are present in khoa? ...... 13 ...... Heat Desiccated Products 1.8 LET US SUM UP

Traditional or indigenous dairy products have great significance in our country. These are the dairy products made and consumed since ancient times. About 50% of total milk production in India is converted into traditional dairy products owing to their high demand by all segments of our population on all religious, social and festivities occasions. The traditional dairy products are classified into six categories on the basis of the principle involved in their manufacture, viz. a) heat desiccated; b) heat and acid coagulated; c) fermented; d) frozen; e) fat phase inversion or fat concentrated and f) cereal based. Khoa, rabri and basundi are the popular heat desiccated dairy products. Khoa is an intermediate product used for manufacture of burfi, peda, gulabjamun, milk cake, kalakand, etc. whereas rabri and basundi are consumed directly in sweetened form. As per the PFA definition, khoa is a product obtained from cow or buffalo milk or their combination by rapid desiccation and should contain not less than 30% fat on dry matter basis of the product. Three types of khoa, viz. Pindi, Dhap and Danedar are available in market. They have different BIS standards, characteristics and end uses. Rabri is also prepared by heat desiccation of milk and adding sugar to desiccated milk. The unique characteristic of rabri is its flaky texture, which is due to addition of malai (clotted cream). In case of basundi the texture is rather smooth and homogenous. All these products have typical heated/cooked flavour, which is considered desirable attribute of heat desiccated products. The composition of khoa, rabri and basundi sold in market vary to a large extent depending on many factors, such as type of milks, composition of milk, degree of concentration, level of sugar addition (in rabri and basundi), packaging, handling and storage conditions. Since all the milk solids are concentrated during heat desiccation, these products have high nutritive value. During manufacture of heat desiccated dairy products many physico-chemical changes take place in milk. The removal of moisture leads to change in the physical conditions. Casein and whey proteins are heat coagulated and exist in aggregated form in which part of fat globules and moisture are entrapped. The release of sulphydryl compounds is responsible for slight cooked flavour in these products. 1.10 KEY WORDS

Additives : An ingredient or a combination of ingredients added, usually in small quantities, for shelf life extension, flavour improvement, increase in nutritive value and to improve functional properties. Clotted cream : A fat rich portion of milk formed on the interface of undisturbed hot milk (temperature 90-95oC) and air due to interaction between denatured protein and lipids. It is called malai in India. Coagulation : Changing liquid milk into a curd like or lumpy- mass-like state by using heat and/or acid or enzymes or combination of these agents. Emulsion : Emulsions are dispersed system, usually of two immiscible liquids. When the outer phase 14 consist of water and inner of oil, as in case of milk, it is considered as an “oil-in-water” type Definition, Composition and emulsion. Standards of Khoa, Rabri and Basundi Heat desiccation : Removal of water from milk by application of heat. Keeping quality : The time (hours/days/months) elapsing from production of a dairy product till it is consumed without any deterioration/spoilage. 1.11 SOME USEFUL BOOKS

Anantakrishnan, C.P. and Srinivasan, M.R. (1964). Milk Products of India, ICAR Publications. Aneja, R.P., Mathur, B.N., Chandan, R.C. and Bajerjee, A.K. (2002). Technology of Indian Milk Products, A Dairy India Publication, Delhi. De, S. (1980). Outlines of Dairy Technology, Oxford University Press, New Delhi. IS: 4883 (1980). Specification for khoa. Bureau of Indian Standards, Manak Bhavan, New Delhi. Rangappa, K.S. and Acharya, K.T. (1974). Indian Dairy Products, Asia Publishing House, New Delhi. 1.12 ANSWERS TO CHECK YOUR PROGRESS

You answers should include the following point Check Your Progress - 1 1) i. Traditional dairy products are those, which are manufactured and consumed in India since ancient (vedic) times. ii. About 50% of the total milk production is utilized for the manufacture of traditional milk products. 2) The important benefits of manufacture of traditional dairy products are: i. Simple methods of their manufacture ii. Do not require expensive and complicated equipment. iii. Can be easily adopted on small scale under rural conditions/collection centres thereby saving in transportation costs. iv. Shelf life is more than fluid milk. v. Value addition. vi. Generate employment. 3) Following is the classification of traditional milk products. i. Heat coagulation and desiccation: Khoa, khoa based sweets, rabri, basundi. ii. Heat and acid coagulation: Paneer/chhana and chhana based sweets. iii. Fermentation: Dahi, chakka, shrikhand, misti dahi.

15 Heat Desiccated Products iv. Phase inversion and concentration of fat: Makkhan and ghee. v. Freezing: Kulfi/ kulfa, icecream etc. vi. Mixing of cereals with milk solids and sugar: Payasam, kheer Check Your Progress - 2 1. i. According to PFA rules, khoa is a heat desiccated product obtained from cow or buffalo milk or a combination thereof and shall contain not less than 30% fat on dry matter basis of the finished product. ii. About 3 million kgs khoa per day. iii. Several varieties of burfi and peda, gulabjamum, kalakand, milk cake etc. 2. i. Three types of khoa, namely Pindi, Danedar and Dhap are marketed in India. ii. – Pindi khoa is available in form of circular balls of hemispherical shape.It has smooth and homogenous texture, characteristic heated/cooked flavour and used for burfi and peda making. – Danedar khoa as name indicates, is characterized by its granular texture. This type of khoa is used for making milk cake and kalakand. – Dhap khoa has higher moisture and thus loose and weak body but smooth texture. It is used for making gulabjamun and pantua. 3. i. There are wide variations in the composition of market khoa. But buffalo khoa prepared under laboratory conditions or by adopting a standard method should contain on an average; moisture, 32%; fat, 24.2%; protein, 18.3%; lactose, 22%; and ash 3.5%. ii. The main factors that affect the chemical composition of khoa are: i) type and quality of milk; ii) method of preparation; iii) concentration level; iv) handling and packaging conditions and v) storage conditions. 4. i. Clotted cream also called as malai, is a skin formed on the interface of undisturbed hot milk (85-90oC) and air. ii. This is an important ingredient of rabri. The typical desired flaky texture in rabri is attributed to clotted cream. iii. Rabri and basundi are both heat desiccated sweetened milk products, but the former contains very distinct flaky texture and is more viscous whereas latter is more homogenous in consistency. Check Your Progress - 3 1. i. Since all the milk solids are in concentrated form in khoa, rabri and basundi, they provide high energy. Normally Pindi khoa provides 400 kcal/100 gm of energy whereas rabri and basundi provide 280 and 250 kcal/100g respectively. These products are also rich source of minerals, particularly calcium. ii. Khoa contains higher percentage of all milk solids, viz. fat, protein and lactose, hence provide more energy. 2. i. During khoa making milk is continuously heated at atmospheric pressure, which leads to concentration of milk solids and many other physico chemical 16 changes. ii. The whey proteins are heat sensitive and their denaturation and complexing Definition, o Composition and with k-casein starts when heating temperature reaches about 80 C. The Standards of Khoa, rate of denaturation increase with the increase in heating temperature. Rabri and Basundi iii. Milk casein, though very stable to heat treatment, also starts coagulation with the increase in size of casein micelles due to increase in concentration of milk solids and also complexing of whey proteins. 3. i. The lipids in milk are present in form of fat globules stabilized by a membrane and are dispersed in serum phase. Vigorous scraping and stirring disrupt the fat globule membrane. The part of the fat is then entrapped in casein aggregate and the remaining in free form. ii. Lactose, the milk sugar, is present in form of true solution. On heat desiccation, it concentrated into super saturated solution. iii. This results into formation of insoluble or undissociated salts of Ca and Mg with increasing milk concentration during khoa making. This will affect the stability of casein and favour the heat coagulation of milk proteins in khoa.

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