Technology Dariy Products Notes1

7/30/2019 Technology Dariy Products Notes1

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CONTENTS

S.No Title Page No

1 STATUS OF MODERN AND TRADITIONAL MILK PRODUCTS IN

INDIA

2

2 HERITAGE OF INDIAN MILK PRODUCTS 7

3MILK IN DAILY DIET

9

4PHYSICAL CHEMISTRY OF MILK

11

5CREAM

18

6 BUTTER 29

7 GHEE 47

8 CONDENSED MILKS/ EVAPORATED MILK: 569 DRIED MILK 75

10 CHEESE 91

11 ICE CREAM 112

12 KHOA AND ITS PRODUCTS 127

13 GULABJ AMUN 129

14 BURFI` 133

14 KALAKAND 140

15 MILK CAKE/PEDA/RABRI/KURCHAN 144

16 CHHANA AND ITS PRODUCTS 153

17 PANEER AND ITS PRODUCTS 171

18 KHEER AND RELATED PRODUCTS 184


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STATUS OF MODERN AND TRADITIONAL MILK PRODUCTS IN INDIA

In the new millennium, the global dairy industry is in search of initiatives to enlarge its market.

One factor that has lent urgency is the crisis created by a continuing decline in world dairy commodity

prices. In April 2002, they touched a new low. This has occurred despite no significant change in the

demand and supply of dairy products. The price drop has triggered a rethinking on the future shape of

global dairy markets. The factors that are expected to re-shape the industry are:

A shift in the global trade away from bulk milk commodities such as SMP, butter and butter oil towards

value-added products such as cheese, yogurt, desserts and speciality milk powders. The

sophisticated consumer now sees food-particularly dairy products-as a means of health and

happiness. He is looking for delicacies that are delightfully tasty and healthy as 'well as authentic and

exotic.

The developed world is reviewing its policy focus on the "surplus" bulk commodities. The aim is to

reduce the stock of subsidized bulk commodities so as to lighten the fiscal burden on the developedcountries. Incentives may have to be given to develop dairy markets as well as production of value-

added milk products.

The growing competitiveness, triggered by the WTO, has made the global dairy markets increasingly

complex. Each year, a large number of new food products are being added in the marketplace in

response to the consumer's search for delicacies that are novel but natural with a touch of mystery

and class. At one end of the spectrum is the high-volume market for lowpriced products. At the other

end is the niche market for high-priced products that are unique in terms of exotic taste and flavour.

The dairy exporters have to identify which market they would like to tap-the low-profit "mass" marketor the high-profit "class" market.

World milk production is projected to rise to 615 million tonnes in 2005 from 534 million tonnes

that was averaged during the 1993-95 period. By 2005, the milk output of the developing as well as

developed regions would be almost on par at about 250 million tormes (Table 1.1.2). These trends are

reflected in a study of the FAa Commodities & Trade Division that has made a ten-year projection for

world milk production between 1995 and 2005. A notable feature of the scenario projected by the FAa

study is the growing importance of milk from dairy animals other than cows. For example, the Indian

sub-continent contributes a substantial 90 per cent to the world buffalo milk production. Overall, in thedeveloping world, the milk from buffaloes, goats, sheep and camels accounts for 15 per cent of the

world milk production, and this share is expected to increase in the corning years.

Trends in dairy commodity export prices, 2001-2002


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Commodity April February March April2001 2002 2002 2002

Skimmed milk powder 2,038 1,574 1,473 1,371Whole milk powder 2,000 1,549 1,488 1,416Acid casein 5 300 4 600 4 449 4 280Cheddar cheese 2,025 1,987 1,924 1,880Butter 1,275 1,094 1,036 1,001

Source: FAO Food Outlook, May 2002.

Dairy markets in the new millennium are being increasingly shaped by the twin strands of globaliza-

tion and localization. The spotlight is on the developing world that has shown a remarkable growth in

disposable income accompanied by rapid urbanization. The share of this region would be 79 per cent

in the projected increased milk production (Table 1.1.2). Significantly, in this growth, India alone is

expected to account for a 30 per cent share. For most developed countries, the growth would be

marginal, with their milk consumption and population expected to plateau.

Changing Market Profile: Essentially, the following factors are moulding the market profile in the

developing countries:

1. Increased urbanization and income growth:This global phenomenon has become a major force in

the developing world. According to the UN projections, 22 out of 26 urban agglomerations of over 10

million population in 2015 would be in the developing countries. Already, this trend is reflected in India

and China where tens of millions of people are moving from villages to cities and towns. With

urbanization has corne increased disposable income and consequent demand for greater variety in

value-added food, largely in decline in the demand for tirmed and dried milk powders and a rise in that

of packaged, fresh dairy products. Its related spin-off is the growing importance of supermarkets in

cities and the refrigerator in the urban kitchen of an average middle class family.

2.Health and pleasure:The consumer today demands health benefit in what he eats. On this basis,

dairy products rank among the top. They enjoy a positive image in terms of quality and health

benefits. For example, the probiotic yogurts, using live bacteria culture, are considered health-

promoting products. However, another trend that circumvents the fitness concern is a preference for

"full-tasting" food products. More and more consumers are choosing full-fat products such as ice-

cream, cheese or desserts for the real pleasure of eating, disregarding the health concern. This

change is reflected in the increasing production of full-fat ice-cream since the early 1990s in the

United States, reversing the earlier trend in favour of low-fat icecream. Similarly, in some countries,

butter is once again seen as a "natural" product, and its consumption is gaining ground.

3.Eating out: In many countries, the main growth in food expenditure is in the area of food eaten

outside the home. Even for meals eaten at home, greater emphasis is on the convenience that is


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provided by instant heat-and-eat dishes and snack foods. The rising food consumption outside the

home has posed a new challenge to the dairy industry, as its products are so closely linked with the

kitchen.

A highly visible manifestation of the eating-out phenomenon is the rapid growth of the "fast-food"

industry. Its secret of success is that it converts a Rs 50-foodstuff into a Rs 500-meal, and this pattern

has been repeated millions of times in hundreds of cities all over the world. The growth of this sector

has also given a push to the consumption of dairy products like ice cream, milk shakes, and cheese

which figure prominently on the fast-food menus.

How does the common man select the food he chooses to eat? A marketing consultant, Mr

Xavier Terlet of XTC, a French market intelligence consultancy, has summed up this situation thus:

Most people eat for pleasure. It dictates all consumer demands. It implies something different, a shift

in habits. To satisfy the consumer's desire for pleasure, three new trends are emerging as far as taste

is concerned in the popular dairy product segments:

CD Authenticity: An emphasis on 'tradition', 'real', and 'purity' in tastes that offer a homely appeal

(natural tasting, earthenware pots, etc).

CD Variety: An abundance of new textures, colours and names that never cease to amaze

consumers, designed to appeal to different segments. Products for adults are also becoming

increasingly sophisticated (with fruits, cereals, creamy, thick textures). Children, meanwhile, prefer

colourful and personalized products, small formats rather than refined tastes.

CD Exoticism: A constantly evolving trend that seeks to supplant 'ordinary' products by emphasising

specific tastes, characteristics of faraway, exotic places (Africa, Asia, LatinAmerica, etc). The aim is to

stimulate the imagination and whet the consumer's appetite.

Tradition Reinvented: Of late, dairymen have realized the need to change the image of milk as only a

health/ nutritive product that people must consume (a sense of "compulsion") to a mod image of "like

to" (a sense of choice) for pure pleasure. This would be possible by widening the choice of dairy

products and adding into them authentic, exotic flavours.

One exciting group that can tickle the taste buds of the young generation is the wide range ofethnic

dairy delicacies. Significantly, they have enough variety to serve both the' class' and 'mass' markets.

A recent FAO publication lists over 300 ethnic products in about 100 developing countries of Asia,

Africa, Latin America and the Middle East (Table 1.1.3). Most of them have been popular from time


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immemorial and offer a range that is delightfully different in terms of look, taste and flavour.

These products are part of the world heritage and embody the tradition of excellence. They are being

"reinvented" by applying modern process technologies for mass production to meet the consumer's

new demands in response to changing lifestyle that combines purity, quality and convenience with the

nostalgia of a bygone era. They represent an exciting opportunity as well as a challenge before the

world dairy industry to expand its market range. Their bigger operating margins also provide new

avenues to the industry for value addition to add to its profitability.

Time is ripe to expand production and marketing of traditional sweets. Some of them are very fragile

and delicate to process and handle. The manual skills required for their preparation are not easy to

duplicate by machines. Besides, there is a need to incorporate into their processing the international

norms of food safety and hygiene and to adopt latest packaging systems for extending their shelf life.

Recent advances in dairy technology provide know-how to increase the shelf life of ethnic products.

The advent of convenience foods and their increasing acceptability has given a boost to the

modernization of the traditional dairy sectoc. Bringing ethnic dairy products into the mainstream of

dairy foods would also have a positive impact on the livelihood of the rural poor who form the bulk of

millions of dairy producers in developing countries. This trend will help them get a better procurement

price for the milk they sell.

Heritage of Indian Milk Products

The flavour of the new millennium is India's ethnic milk-based sweets, desserts and puddings. Each

product has its distinctive wisdom as it evolved through the ages, continuing to surprise the gourmet

even today. Milk and milk products are highly valued in Indian society as a source of nutrition. This

concept has withstood the test of time, notwithstanding the cholesterol scare.in the West.

In India, milk sweets are an inseparable part of wedding ceremonies, feasts, festivals and social and

religious occasions. Boxes of sweets are a harbinger of good news, be it a birth or betrothal in the

family, anniversaries, success in examination, landing the first job, promotion and the like. The

expression to convey the good news says it all: "Sweeten your mouth." rn fact, one of the most

popular and oldest Bengali sweets is named" sandesh" (message).A box ofit accompanies the good

news that a family wishes to announce in its social circle.

The products developed, either for direct consumption or as an intermediate base material, have

followed ageold methods of preservation and conservation through heat desiccation, fermentation,


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coagulation and clarification. The aim is to recover the total solids to the maximum extent through tiny

scale/household level processes and technologies that are adequate and appropriate to local

situations, resources and food habits.

From time immemorial, milk and milk products have enjoyed an eminent position in the Indian food

ethos. The value of their output exceeded Rs 1,000 billion in 2001 (Table 1.1.4). Of this amount, the

output of traditional dairy products is estimated at over Rs 570 billion (Table 1.1.5), while the

organized sector accounts for Rs 170 billion (Table 1.1.6). The share of the indigenous products -

branded mithais and ghee -in this sector is at present only Rs 56 billion, but it is expected to rise

rapidly in the coming years.

cheese and milk powders. They can do wonders for the organized dairy sector to better its prospects

of financial stability and steady growth. A number of modern dairies have already taken to the

production of popular milk products like burfi, gulabjamun, rasogolla, shrikhand, kheer, paneer, peda,

curd, lassi. Some of these products have registered a high growth rate, ranging from 15 to 20 per

cent. This development is also having a trickle-down effect on the traditional dairy sector which has

taken up modernization of its age-old mithai-making methods and product formulations in the

following ways:

Inducting appropriate technologies for large-scale production;

Using modern packaging systems and labelling to meet the emerging consumer demand for extended

shelf life and product information;

Evolving a quality assurance system to meet the international standards of food hygiene and product

safety; and

Collecting market intelligence to inspire confidence among prospective entrepreneurs to take to

commercial production of traditional products in India and abroad.

The market for value-added indigenous dairy products is set for a rapid growth. This

development marks the second wave of India's White Revolution that is transforming the face of the

dairy industry. The first wave made India the world's biggest milk producer and the biggest market.

The second wave is boosting the organized sector and will make it a significant segment of the

industry with its market share doubling from the present 10-12 per cent of milk processed. A new

market of over Rs 50,000 million is expected largely from ethnic foods such as flavoured milks, dahi,

paneer, buttermilk, lassi, gulabjamun, shrikhand and kheer. It will largely meet the new demand

created by the increasing purchasing power and disposable income of the middle class in India's

urban and rural areas.


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Milk in Daily Diet

Pastoral economy formed the basis of the Indian civilization, with dairying as its integral part. Dairying

took roots in the north-west part of the country and spread virtually to the whole of the sub-continent.

India is regarded as the first country to have developed products like dahi (yogurt), makkhan and

ghee and to use them in daily diet.

In the Indian food ethos, milk mixed with cereals and pulses has been regarded as the staple

food. Several references in the ancient Indian literature commend this blending for their 'satvik'

(positive/godly) attributes. These have also been promoted as ideal food for persons pursuing spiritual

and higher academic pursuits. Food in ancient India was not merely a means of sustenance of life, but

part of a cosmic moral cycle. This belief, by and large, holds good even today in the Indian sub-

continent, as is reflected in the popular proverb: "You are what you eat."

The manner in which a farm family uses milk is indicative of the evolutionary process of

indigenous dairy products. Traditionally, farmers boil the milk immediately after milking, which extends

its shelf life. Boiling of milk is specific to the Indian sub-continent and is necessary to store it without

refrigeration. Farmers consume as much milk as they can in the morning along with their meals; and

the remaining milk is converted into dahi in the evening, which is primarily done to preserve milk

overnight.

The following morning, a small portion of dahi is consumed by the family and the bulk of it is

churned to produce makkhan and ghee. The by-product of churning, chhach, is consumed by the

family in liberal quantities, and the remaining is freely distributed in the neighbourhood among other

villagers. Both dahi and lassi provide ways of consuming cultured products for better health. Hot milk

is widely consumed before going to bed as a nightcap. The milk is, at times, flavoured with

condiments such as almonds, cardamom, dry dates, etc. Evolution of dahi, makkhan, chhach and

ghee, apart from adding to the variety of milk products, also provided ways and means of conserving

milk nutrients for long periods.

Milk plays a major role as a source of animal proteins in the average Indian diet that is largely

vegetarian. As much as 46 per cent of milk produced in the country is consumed as liquid milk that

reflects its importance in the national diet. The average per capita milk availability in 2001 was 226

grams/day, exceeding the recommended level of 220 grams.


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Boiling milk before consumption is essential to extend its shelf life without refrigeration. Boiling

does not affect the availability of calcium and vitamins (except C) in milk. Heating to the first boil

results in destroying most of the pathogens. This practice explains the virtual absence of milk-borne

diseases in the country.

Dahi (curd) is widely consumed along with meals. During dahi preparation, fermentation of

milk with lactic cultures checks putrefactive changes and imparts an acid taste to the product, which is

particularly refreshing in a hot climate. Following fermentation of milk, a greater amount of phosphorus

and calcium is made available to the digestive system by their precipitation in the lower intestines.

Thus, dahi in its different forms-chhach, lassi, kadhi, shrikhand, etcenhances the nutritive value of the

average diet.

Makkhan and ghee provide as much as one-third of the fat in the Indian diet. Over the

centuries, Indians have cultivated a liking f9r the aroma and flavour of ghee as a cooking medium for

various food preparations, including sweets.


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PHYSICAL CHEMISTRY OF MILK

Milk is the physiological secretion of normally functioning udder. It is a very complex substancehaving many characteristics and physical properties, the knowledge of which, is essential since itwill be useful when milk is used to prepare products and when it is subjected to many processingto make it safe.

Water is the dispersion media for other solids. It is in continuous phase of liquid to which theconstituents are dispersed. Solids exist in 3 states of dispersion. They are,

Coarse dispersion [particles greater than 0.001 mm]Colloidal dispersion [particles between 0.001 mm and 0.000001 mm]Molecular dispersion [particles Less than 0.000001 mm].

Materials in solution:Materials in solution are called materials in molecular dispersion. These include most of salts,

lactose, part of albumin, globulin. A true solution is defined as one in which the molecules aredispersed individually. Some of the albumin and globulin, which are large in size, also exist incolloidal state.

Materials in colloidal dispersion:Here the particles are microscopic but they are large enough to be held by an ultra filter. E.g.

Calcium caseinate, part of albumin and globulin and calcium phosphate. These can be separatedby dialyzing through appropriate membrane [semi permeable membrane]. For the suspension ofthese colloids, certain materials are required and these are called as stabilizers. In milk, thecolloids themselves function as stabilizers to each other.

Materials in coarse dispersion:Butterfat is suspended as tiny spherical particles called fat globules. Cellular constituents also

come under this category [E.g. In mastitis, leukocyte count of milk exceed 5 lakhs]. Fat particlesvary in size from 0.1 to 10 in diameter, with an average of 3.1 ml of milk will containapproximately 2-4 million fat globules.

PHYSICAL PROPERTIES OF MILKMilk acidity:

pH of milk is approximately 6.6, which lies on the acid side of neutral (7). Fresh milk drawn fromthe udder possesses a certain acidity termed as natural acidity, which has to be distinguished fromdeveloped acidity in the form of lactic acid. Normal acidity or natural acidity is due to casein, acidphosphates and citrates and to a lesser extent by albumin, globulin and CO 2. Natural acidity variesfrom one cow to another. It ranges from 0.08-0.30%. Colostrum has high natural acidity becauseof its high protein content. Acidity is higher than normal during the early lactation period. It falls tonormal in about 2 months of lactation.

Titrable acidity or total acidity is equal to natural acidity and developed acidity. Natural acidityis also called as apparent acidity. Developed acidity is also called as real or true acidity. Titrableacidity is used as rapid platform test for accepting or rejecting milk and to find whether the milk issuitable for heat processing, because the developed acidity lowers the temperature of heatcoagulation of casein. 0.18 to 0.19% is taken as a deciding line between satisfactory andunsatisfactory milk samples.

Milk of high natural acidity is usually high in their total solids content. They have a fair quantity ofbuffering substances like proteins, phosphates and citrates, which resist changes in pH whenacids or alkali are added. So milk of high natural acidity is highly buffered. Such milk requires


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more lactic acid to develop before the pH reaches the isoelectric point of casein [pH 4.6] whichmeans that a longer time will be required before such samples curdle at ordinary temperature.High natural acidity increases the keeping quality.

Colour:Characteristic white colour or white opalescence of the milk is due to scattering of light by the

colloidal particles. Yellow colour of the milk is due to the carotene. The intensity of yellow colour

increases in cow milk when they are fed with green fodder. Buffalo milk is white in colour due tothe absence of carotene which is efficiently converted to vitamin A. Dilute acid or rennet whenadded results in coagulation of casein and fat and the separated whey will be having a distinctgreenish yellow colour due to the pigment riboflavin.

The colour of the opaque object is the colour it results. The colours of the visible spectrum areabsorbed. Thus an object is yellow because more yellow light is reflected to the eye than anyother colour. (A white object reflects all the colours of the light that fall on it while a black objectabsorbs all of them).

Flavour:A property very difficult to define. It is a combination of taste and smell. Milk has a

characteristic mild, pleasant flavour. Sweet taste of lactose is balanced against the salty taste ofchlorides. Some research workers attribute the rich flavour of milk to the fat present in milk. Aslactation advances, lactose declines while chloride increases; the taste is deflected towards salty.A similar effect is caused by udder infections. When odouriferous substances like garlic are fed,milk gets the characteristic taste, by its passage to the milk from the blood. Milk also absorb thevolatile vapours present in the atmosphere. Both these types can be avoided by feeding suchfeeds immediately after milking. Feeding molasses and beet by-products sometimes causes fishyflavour. Metals like copper acts as a catalyst to develop oily taints if it is present in a concentrationof 3 ppm; it imparts a metallic taste. Cows suffering from ketosis produce milk with cowy odourdue to entry of ketone bodies from blood to milk. As lactic acid develops, the flavour of milkchanges towards characteristic sour odour. This is due to the production of various by productslike butyric acid, diacetyl, etc.

Specifi c gravity:The term specific gravity as applied to milk means the weight of the given volume of milk

compared with the weight of same volume of water at the same temperature

Average specific gravity of milk and its components at 60F (15.6C)Cow milk : 1.028-1.030Skim milk : 1.035-1.037Buffalo milk : 1.030-1.032Water : 1Fat : 0.93

Protein : 1.346Lactose : 1.666Salts : 4.12SNF : 1.616

The variation in specific gravity of different individuals milk is due to the flocculation in water,fat, protein, lactose and minerals of milk. There will be difference in specific gravity of liquid fat andsolid fat. One of the peculiarities of milk fat is that there is appreciable time lag in adjusting itsphysical condition to a change in temperature. Addition of water lowers the specific gravity. Highfat milk has low density. Removal of fat results in separated milk or skim milk or defatted milk,which has a higher specific gravity, can be restored by adding water.


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Specific gravity is lowered by addition of water, addition of cream or by increasing thetemperature, while the contrary effect is caused by addition of separated milk or skim milk,removal of fat or lowering the temperature.

Recknagel phenomenon:The specific gravity of freshly drawn milk is low. It increases by 0.001 as time advances. This is

due toPartial cooling and solidification of fatHydration of proteinLoss of CO2Escape of air bubbles.

Surface tension:Surface tension is due to the force of attraction between molecules. When compared to watersurface tension of milk is low. The surface tension of milk at 20C is 54.5 dynes/cm. It decreasesas the temperature is raised (at 60C it is about 40-45 dynes/cm). The presence of fat lowers thesurface tension. Whole milk has a slightly lower surface tension than skim milk and that of creamis still lower. Milk and cream on aging undergo a slight decrease in surface tension. Colloidal

constituents like proteins also lower the surface tension along with fat globules. The substances,which lower the surface tension, will get concentrated at the liquid air interspace. When milk iswarmed, calcium caseinate gather at the liquid air interspace together with small amount of fatglobules, albumin & globulin. If milk is agitated similar concentration occurs around the air bubbles& the phenomenon of frothing or foaming occurs.

Recknagel found that the specific gravity of freshly drawn milk was lower than the specificgravity subsequently obtained, after an hour or later. He found that the rise in specific gravity to beregular, more rapid at lower temperatures than at higher ones and to amount on an average of0.001. This is called Recknagel's phenomenon.

Viscosity:The viscosity of a substance refers to its resistance to flow. It is a measure of frictionbetween molecules as they slide. Milk is considerably more viscous than water mainly on accountof fat emulsion and colloidal particles. Homogenization increases viscosity. Increase intemperature causes reduction in viscosity. At 20C, milk will be half viscous as it is at 0C and at40C, it will be 1/3rd viscous as it is at 0C.Oxidation-reduction potential:

Incase of organic materials, oxidation is defined as the uptake of oxygen or loss of hydrogen.In the same manner, reduction may be defined as the process of loosing oxygen or gaininghydrogen. In ionic system, it can be demonstrated that phenomenon may involve loss or gain ofelectrons. In practice, the potential difference created by platinum electrode in a solution of anoxidant or reductant is measured by completing a circuit through calomel half-cells and apotentiometer. The voltage measured under these conditions reflects the oxidizing or reducingcapacity of the solution. This potential is called as oxidation-reduction potential or O-R potential(or) redox potential and is designated by Eh.

The O-R potential of milk normally falls within the range of +0.2 to +0.3 volts. In milk, the O-Rpotential is controlled by the following substances.Dissolved O2Ascorbic acidRiboflavinLactoseCysteineCystineMilk under anaerobic conditions as in udder has O-R potential of 0.13 volts. It increases to +0.3volts on contact with air in the atmosphere. The bacterial action reduces the O-R potential.


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Methylene Blue dye Reduction Test (MBRT) is based on the principle of lowering of the O-Rpotential through use of available oxygen by the microorganisms.

Refractive index:Milk has a refractive index of about 1.35 and that of water is 1.33. So addition of water lowers therefractive index.Boiling point:

Boiling point of any liquid is the temperature at which at the given pressure the material is inequilibrium both as a liquid and as a gas. This is the temperature at which the liquid phase willvaporize and the gas phase condense or liquefy according to the heat supply.

Water boils at 100C under normal atmospheric temperature and pressure. The presence ofdissolved substances increases the boiling point of a solution. Since milk contains severaldissolved substances, it has higher boiling temperature than that of water. Because there isvariation in the dissolved substances, the boiling point of milk also varies between 100.15-100.17C [100.2-101.02].

Freezing point:The freezing point is the temperature at which, at a given pressure, a material is in

equilibrium as both a solid and as a liquid. This is the temperature at which the liquid phase mayfreeze or crystallize and the solid phase may melt or liquefy.

Pure distilled water freezes at 0C under normal atmospheric pressure. Milk freezes at atemperature slightly lower than that of water due to soluble constituents like lactose, soluble salts[chlorides] which lower and depress the freezing point [to an extent of 75% total depression]. Fatand protein, two variable constituents of milk will have very little influence on the freezing pointdepression. The range of value is 0.525 to 0.565C [-0.55C]. Season has no influence onfreezing point. By determining the freezing point in milk, it can be ascertained whether water isadded or not. The equipment used to determine the freezing point of milk is Hortvet cryoscope.Percentage of water

added to milk = T-T' X 100TT =normal freezing point [-0.550c]

T' =observed freezing point of the given sample.The addition of 1% water to milk will raise the freezing point by 0.0060c.Limitations of freezing point estimation:It is unable to find out addition of separated milk.It is unable to detect the removal of fat in milk.Freezing point is seriously affected by the developed acidity.Electrical conductivity:In a pure solution, the conductivity is a function of the ionic concentration. In an heterogeneoussystem such as exists in milk, the fat and the colloidally dispensed substances obstruct the ions intheir migration and decrease the conductivity. The electrical conductivity increases with increasein temperature. About 80% of current in milk is carried by chloride ions [chloride content increasesduring mastitis]. The electrical conductivity value of cow milk is 0.005 ohm-1 cm-1 at 25C.

Adhesiveness of mi lk :When a piece of paper is moistened with milk, it sticks to surface of wood or glass or metal

due to casein glue.

Cream Raising:When milk is allowed to stand, fat rises to the top and eventually forms a layer packed with

fat globules called cream. This is due to the difference in the specific gravity of serum and fat. Onedrop of milk contains about one lakh globules with the diameter varying from 0.3 to 10.

Foaming:


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It is due to materials that lower the surface tension like milk protein and fat. Milk fat not onlyincreases the foaming, but also increases the stability of the foam.

CREAM

Cream has been known from time immemorial as the fatty layer that rises to the top of the milk

when it stands undisturbed for some time.

Cream may be defined as that portion of milk which is rich in milk fat or that portion ofmilk into which has been gathered and which contains a large portion of milk fat, or whenmilk fat is concentrated into a fraction of the original milk, that portion is known as cream

According to the PFA rules (1976), cream, excluding sterilized cream, is the product of cow orbuffalo milk or a combination thereof, which contains not less than 25 per cent milk fat. Cream isrich in energy giving fat and fat-soluble vitamins A, D, E, and K, the contents of which depends onthe fat level in cream.

Classification

Cream may be classified broadly as:

Market cream, which is used for direct consumption,Manufacturing cream, which is used for the manufacture of dairy products.

The various types of cream are

Table creamLight cream contains 20-25% milk fat.Coffee cream.

Whipping cream Contains 30-40 % milk fat, andHeavy creamPlastic cream contains 65-85 % milk fat.

Composition of cream:The chemical composition of cream is given below.1. Water 45.45-68.2 %

2. Fat 25-60 %

3. Protein 1.69-2.54 %

4. Lactose 2.47-3.71. %

5. Ash 0.37-0.56 %

6. Total solids 31.8-54.55 %

7. Solids not fat 4.55-6.80 %.

The formula for determining the solids not fat (SNF) content of cream is

100 - % fat in cream% SNF in cream = X % SNF in milk.

100 - % fat in milk


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Cream is obtained from milk by either gravity or centrifugal separation methods. The basicprinciple of cream separation is based on the fact that milk fat is lighter than the skim milk portion.At 16C, the average density of milk fat is 0.93 and skim milk 1.036. Hence when milk is subjectedto force, the two components, viz., cream and skim milk, by virtue of their differing densities,separate from one another.

Uses of cream:

For direct consumption as table cream /coffee/ whipping creams,In the preparation of special dishes,In the production of plastic , frozen and cultured creams;In the manufacture of butter, cream, ice cream, butter oil and ghee

Method of cream production

Gravity method:

When the milk is allowed to stand undisturbed for some time, there is a tendency for the fat to riseis given by he following equation, which is known as Stokes Law:

V = 2G (ds - df) r2nwhere,V = velocity or rate at which a single fat globule risesG = acceleration due to gravity.ds = density of skim milkdf = density of fat.

r = radius of fat globules.

n = viscosity of skim milk.

From the stokes law it can be observed that theoretically, velocity is increased by

Increase in radius of fat globules:Increase in difference in densities of skim milk and fatDecrease in viscosity of skim milk.

The rate of rise of fat globules in gravity methods is affected by

Size of fat globules: as the size of fat globules increases, the rate at which cream rises alsoincreases.

Temperature: As temperature increase, viscosity decreases and hence the velocity increases.A clump or cluster acts like a single globule in so far as movement through skim milk is concerned.Gravity methods being very slow, are no, longer used commercially for cream separation.

II. Centrifugal method:

Centrifugal cream separators are similar to clarifiers in that they consists of a stack of conicaldiscs housed in a separator bowl and rotated at high speed by an electric motor.


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The Separator

The separator is a unit, which removes most of the milk fat from milk by centrifugal force. Itsprincipal components are

power source, a separator bowl, a set of gears and shafts, a product inlet and a product outlet forcream and skim milk.

The separator bowl consists of an outer shell within which are a large number of cone shapeddiscs constructed so that between each pair is a very small space of not more than 0.5mm. Asthe milk enters the bowl, it is distributed into these spaces between the discs; it is immediatelysubjected to a tremendous force. While both the fat and skim milk subjected to the centrifugalforce, the difference in density affects the heavier portion (skim milk) more intensely than thelighter portion (i.e. Cream) thereby the skim milk is forced to the periphery while the fat portionmoves towards the centre. The skim milk and cream both form vertical walls within the bowl andare separated by being led trough separate outlets.

Any insoluble particles in the milk, such as bits of curd or dirt etc., collects as separator slime

and is thrown outward as the bowl operates. These pass along with the skim milk into the spacebetween the outer edge of the discs and the inner face of the bowl shell. Such material isdeposited on this face of the bowl shell, which is removed latter. Separator bowl operate atspeeds as great as 20,000 rpm. The separator is a precision instrument and hence has to be ingood condition and operated properly to get maximum skimming efficiency.

Centrifugal force (F) = K X W X R X N2

Where

W= mass of the revolving body,

R= radius of the circle in which body revolves.,

N= R.P.M of the revolving body.

K= constant.

Stokess law applied to centrifugal separation is as follows

(ds-df)V = r2 N2.R.K.

nWhere

V =velocityn =viscosity of skim milkr = radius of fat globule,ds = density of skim milkdf density of fat,N= speed of the bowlR= distance of fat globule from the axis of rotation.K = constant.

It will be seen from the above that the speed of cream separation is increased by:


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Greater radius of fat globuleGreater difference in density between skim milk and fatGreater speed of the bowlLower viscosity of skim milkGravity and centrifugal cream separation have been characterized.

Characteristics of gravity and centrifugal cream methods

Particulars Gravity methods Centrifugalmethod

Nature of forces causingseparation Gravitational Centrifugal

Speed of separation Extremely slow Practically instant

Direction of movement of fat andskim milk particles

Vertical Horizontal

Bacteriological quality of creamand skim milk

Low High

Fat percentage of cream 0-25 18-85(can becontrolled)

Fat percentage of skim milk 0.2 or above 0.1 0 or less

Scale of operation Small Large.

Fat percentage recovered incream

Not more than 90 99-99.5%

Factors influencing the fat percentage of creamThe important factors that influence the fat percentage of cream by centrifugal cream separationmethods arePosition of the cream screw:The cream screw /outlet consists of a small threaded, hollow screw pierced by a circular orificethorough which the cream emerges. This screw can be driven IN and OUT thus bringing it nearer

to and away from, the center of rotation. Similarly the skim milk screw /outlet for the removal ofskim milk, once the cream screw or skim milk screw has been adjusted, the cream separatordelivers, under normal conditions, a definite ratio of skim milk and cream, which is usually 90:10(or 85:15) by volume. By altering the position of the cream screw or skim milk screw the ratio ofskim milk to cream changes. Thus when the cream screw is IN towards the axis of rotation, ahigher fat percentage in cream is obtained and vice versa. This is because the force tending todischarge cream through the orifice is decreased while that tending to discharge skim milkremains unaltered. Smaller proportions o cream is therefore discharged, which, containing thesame quantity of fat, shows a higher fat percentage. Screwing OUT the cream screw producesthinner cream. Similarly the skim milk screw OUT results in richer cream and vice versa.


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Fat percentage in milk:The higher the fat percentage in milk, the higher the percent fat in cream. And vice versa. Sincepractically all the fat in milk is contained in the cream.Speed of bowls:Higher the speed of the bowl, the higher the fat percentage on cream, and vice versa.Rate of milk in-flow:The higher the rate of milk inflow, lower the fat percentage in cream and vice versa.

Temperature of milk:The lower the temperature of milk during separation, the higher the fat percentage of the creamand vice versa.

Amount of water or skim milk added to flush the bow l.The greater the quantity of water added to flush the bowl, the lower the fat percentage in cream,and vice versa.

Factors affecting fat loss in skim milk dur ing separation:The skimming efficiency (SE) of a cream separator refers to the percentage total fat from milkrecovered in the cream. The higher the fat percentage in milk and/or the greater the fat loss inskim milk, the lower the skimming efficiency and vice versa.The factors affecting the fat loss in skim milk are

Temperature of milk:The lower the temperature, higher the fat loss in skim milk and vice versa. For the efficientseparation the temperature of milk should be above the melting point of fat, so that the milk fat inthe fat globules is uniformly in liquid form. A satisfactory temperature for separation is around40C. The milk is heated before separation to 35-40C in plate or tubular heaters for efficientseparation. This is known as preheating /fore warming of milk.

Speed of the bowl:The lower the speed, the higher the fat loss in skim milk and vice versa. At below rated speed,there will be more fat loss in skim milk because insufficient centrifugal force is generated forefficient cream separation. With above rated speeds, the skimming efficiency will not increasegreatly.

Rate of milk inflow:The higher the rate of inflow, the higher the fat loss in skim milk and vice versa.Position of cream screw:Upto 50% of fat in cream, there is little effect on the fat loss in skim milk, but when the cream fattest is greater than 50-60% there is greater fat loss in skim milk; if above 60% of cream is obtainedstill higher fat loss in skim milk results.Mechanical condition of the machine:Unsatisfactory mechanical condition of the cream separator causes greater fat loss in skim milkthat include, vibration of the separator, conditions of discs, amount of separator slime in the bowl.Size of the fat globule:The greater the number of fat globules of less than 2 microns size, the higher the fat loss in skimmilk and vice versa, as they escape the centrifugal force and to be recovered in cream.

Degree and temperature at which milk is agitated before separation:The higher the degree and temperature of agitation the greater the loss in skim milk and viceversa.Presence of air in mi lk:The greater the amount of air, the higher the fat loss in skim milk.Acid it y of acidit y:The higher the acidity, the lower the efficiency of separation. The higher acidity, the lower thestability of casein particles, which in turn get precipitated and clog the bowl, there by lowering theefficiency of separation.Standardization of cream


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This refers to the adjustment of the fat level in cream to the desired percentage conforming tostandard requirements. The fat percentage in cream is usually adjusted to the prescribed level bythe addition of calculated amount of skim milk by Pearsons square method.Pasteurization of cream

Pasteurization of cream refers to the process of heating every particle of cream to not less than71C and holding it at such a temperature for at least 20minutes, or to any suitable temperature

time combination using approved and properly operated equipment.Objectives of pasteurization

To destroy the pathogenic microorganism in cream so as to make it, and also resultant butter, safefor human consumption.To destroy undesirable micro organisms and inactivate the enzymes present , so as to prolong thekeeping quality of the cream and butter,To complete the neutralization process.To eliminate some of the gaseous tainting substances.To make possible the removal of some volatile off-flavours

Methods

Holding pasteurization:

The cream is heated to 71C for 20 minutes and then promptly cooled.

HTST pasteurization:The Plate Pasteurizer is better suited to freshly separated sweet cream than neutralized cream, asthe latter more easily forms burnt-on films on the plates. The maximum heating temperature maybe 95-100C for 5-16 seconds.

Vacuum pasteurization:This is a continuous process and removes the off-flavours effectively. This process dilutes thecream and it will lower the fat percentage of cream up to 6 - 8 %.

Manufacture of di fferent types of cream:

Sterilized or canned cream:

Sweet cream is standardized to 20% fat, pre-heated to 80C without holding and then doublehomogenized immediately, cooled to 16C filled into tin cans and immediately sealed. It is thensterilized at 118C for 12-15 minutes.

Plastic cream:This is obtained by re-separating normal cream in a normal cream separator, or separating milk ina specially designed cream separator.

Frozen cream.Objectives: To improve the keeping quality of cream during transportation over longdistance, to store surplus cream for use during shortage mainly used by ice cream manufacturerswho add sucrose to cream before freezing to prevent oiling off after thawing. First the cream isstandardized to 40-50% fat, pasteurized at 77CC for 15 minutes cooled to below 4C and filledinto paper /plastic container or tin can and sealed well and then frozen at 12C or below.

Clotted cream:

This is prepared by heating cream to 77-88C in shallow pan and then allowing it to cool slowly.The surface layer consists of clotted cream, which is skimmed off and strained.


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Sour cream:This is a heavy bodied ripened cream of high acidity (0.6%) clean flavor and smooth texturesmade by inoculating sweet, pasteurized and homogenized cream with a culture of lactic acid andallowing fermentation to proceed until these qualities are obtained.

Synthetic cream:

This is mixture of flour, egg-yolk, sugar, water, and vegetable fat usually groundnut oil.

Packaging and storage of table cream:

Packaging: Table cream is packaged for retail sale in units similar to those for milk such as glassbottle, paper cartons LDPE sachets, plastic bottles etc.Storage and distribution: cream is stored preferably at 5-10C and distributed as early as possible,but preferably within three hours of removing from, cold storage.

Defects in cream, their causes and prevention

Name of the defect Causes Prevention

Table cream

Flavour

Cooked flavour Excessive heating ofcream duringpreparation.

Proper heating of creamduring pasteurization.

Feed and weed flavour

Feeding of milk-taintingfeeds and weeds within

3 hours before milking

I) Feeding of milk-tainting feeds and

weeds soon aftermilking

ii)eradication of milktainting weeds

iii)vacuumpasteurization of cream

Highly acid/sour cream

Use of sour milk forseparation.

Acid development incream.

Using fresh, sweet milkfor perpetration.

Neutralization

Oxidized /oily/metallic/tallow.

Fat oxidation due todirect contact of milkwith copper or iron,exposure of milk orcream to sunlight etc.

Proper tinning of milk orcream or cream holdingvessels or usingaluminum alloy orstainless steel ascontact surface.

Vacuum pasteurizationof cream.


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Rancid

Fat hydrolysis due tolipase action in milk orcream.

Inactivating lipase byproper pasteurization ofmilk and cream.

Miscellaneous

Feathering on hotcoffee

excessivehomogenization

pressureUsing sour cream

Addition of salts.

.proper homogenizationpressure

using sweet cream

Avoiding addition salts.

Manufacturing cream

a) Flavor.

Barney

Poor ventilation ofmilking byre/barn

Not keeping milkproperly covered duringproduction.

Proper ventilation ofmilking byre/barn

Keeping milk properlycovered duringproduction.

Bitter

Intake of bitter weedsby milch animals

Lipase activity duringcream separation.

Growth of proteolyticbacteria in cream.

Eradication of offendingweeds.

Checking lipase activityby avoiding the dangerzone during 39-49Cduring raw creamseparation.

Storage of cream at 5Cor below to checkbacterial growth.

Cheesy Growth of proteolyticbacteria leading tocasein breakdown.

Storage of cream at 5Cor below to check thebacterial growth.

Coarse acid-/sour. Uncontrolled aciddevelopment in cream.

Storage of cream at 5Cor below to check theacid development.

Cooked, feed and weed, rancid, oxidized etc.,

Same as table cream Same as table cream.

Fruity

development of by-products of growth ofcertain undesirablemicroorganisms

Storage of cream at5C or below to checkmicrobial growth.


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Utensil Using dirty utensils Using well cleanedutensils

Yeasty Growth of lactosefermenting yeasts.

Storage of cream at 5C

or below to check theyeast growth.


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BUTTER

Butter may be defined as a fat concentrate, obtained by churning cream, gathering the fat intocompact mass and then working it.

According to the PFA rules (1976), table creamery butter is the product obtained from cow orbuffalo milk or a combination there of, or from cream or curd from cow or buffalo milk or acombination thereof with or without the addition of common salt and annatto or carotene ascolouring matter. It should be free from other animal fats, wax, and mineral oils, vegetable oils andfats. No preservatives except common salt and no colouring matter except annatto and carotenemay be added. It must contain not less than 80 % by weight of milk fat, not more than 1.5 % byweight of curd, and, not more than 3% by weight of common salt. Diacetyl may be added as aflavoring agent but, if so used the total diacetyl content must not exceed 4 ppm. calcium hydroxide, sodium carbonate, sodium polyphosphate may be added, but must not exceed the weight ofbutter as whole by more than 0.2 %.

Classification:

Many kinds of butter are found in the market. This differs with the type of cream from, which theyare made, and with variations in the manufacturing process. The types of butter are

Pasteurized cream butter:Made usually from pasteurized sweet cream. Such butter usually has a milder flavour than thatmade from similar cream not pasteurized.Ripened cream butter:Butter made from the cream in which butter culture is added and incubated till the desired acidityand flavour are produced. Properly made ripened cream butter has a delicate flavour which isreferred to as real butter flavourUnripened cream butter:Made from unripened cream.

Salted butter :

Butter to which salt has been addedUnsalted butter:Contains no added salt.Sweet cream butter:Butter produced from cream in which the acidity does not exceed 0.2% in the churned cream.Sour cream:Made from cream in which the acidity exceeds 0.2%.Fresh butter:Butter that does not undergo cold storage.Cold storage butter:

Butter stored at a temperature of about -18C for some time.Dairy but ter (USA):

Made on farm. It is usually made from unpasteurised sour cream, which has not beenstandardized for acidity. This butter generally has a sour flavour due to the high acid content ofcream.Creamery butter:Made in a creamery or dairy factory. It is more uniform in quality than dairy butter.COMPOSITION

According to PFA Rules (1976) Table/Creamery Butter should contain not less than 80% fat, notmore than 1.5 % curd and not more than 3% common salt. The typical composition of Indianbutter has been given below.


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Constituent Percentage

Butterfat 80.2

Moisture 16.3

Salt 2.5

Curd 1.0

Butter is very rich in fat and fat-soluble vitamins.

Method of manufacture, packaging and storage

Receiving milk receiving cream

Preheating Grading neutralization.

WeighingSamplingTesting

Separation

Cream


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Standardization (35-40% fat)

Pasteurization or vacreation

Cooling (20-22C)

Ripening (20-22C)

Ageing (5-10C)

Churning

Washing

Salting and working

Packaging and storage (-23 - -29C)

Details of manufacture:

A) Receiving mi lk / cream:

Unloading of cream:The cans of cream brought to the creamery/butter-making factory are unloaded on the receiving

platform, which is at truck height, and arranged according to the route and the patterns.Grading:Purpose of grading is to pay for the product on the basis of its quality. Cream is graded on thebasis of smell, taste, appearance, touch, acidity and sediment. The technique of grading creamconsists in removing the lid of each can, inverting it and smelling it. Next the cream is examinedfor appearance and the presence of any extraneous matter. Cream for butter making is graded inaccordance with the grades of butter that can be made from it. The cream grades are:First grade cream - sweet or slightly sourSecond grade cream - sour, coagulatedReject grade cream - markedly sour, fermented.

Sampling:

Before sampling, the cream in the cans is thoroughly mixed by a combined rotary and verticalmovements of the plunger/stirrer. If required the lidded cans of cream may be sprayed with hotwater to reduce cream viscosity, and facilitate mixing. Then a representative sample may bedrawn for testing purposes.Weighing:

The cans of cream, which have been accepted, are then weighed and the weight

recorded for accounting and other purposes. First grade creams are tipped directly into the


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main neutralization vats. The cream adhering to the inner walls of the cans is recovered by

inverting the cans over steaming jet for short periods.

Testing:The cream samples drawn are tested for fat, solids not fat, acidity, etc., by standard methods.Neutralization of cream:

Neutralization of sour cream for butter making refers to a partial reduction in its acidity.

Objectives:

To avoid excessive fat loss in buttermilk that results from churning highly acid pasteurized cream.When pasteurizing sour cream, the casein curdles; thereby entrapping fat globules as the bulk ofcurd goes to butter milk this cause high fat loss.To guard against the production of an undesirable off-flavour in cream.To improve the keeping quality of butter made from high acid cream. Salted acid-butterdevelops a fishy flavour during commercial storage at 23 to 29C. Correct neutralization is donebyAdoption of a definite standard of churning acidity. Butter for long storage, the cream acidityshould be reduced to 0.06-0.08% before churning. Butter for early consumption the cream acidityshould be reduced to 0.25-30 % before churning.Testing correctly for acidity take a sample of cream after through mixing,First partially neutralize acid cream with a known quantity of standard alkali, and then treat asabove.Determine the lactic acidity of cream by titration of a fixed weight with a standard alkali usingphenolphthalein as an indicator.

Correct amount of neutralizers to be added:

The considerations are

The quantity of neutralizers to be added to a vat of cream varies with the acidity of cream, the finalacidity desired in pasteurized cream and with the neutralizer compound used.It is necessary; first, to calculate the quantity of lactic acid to be neutralized per 100 kg cream.Then the amount of neutralizer required must be calculated.

There are two groups of neutralizers available for use viz., lime (calcium hydroxide , andmagnesium hydroxide) and soda (caustic soda, sodium carbonate, sodium bicarbonate andsodium sesquicarbonate)The requirement of two selected neutralizers are given in table.

Types ofneutralizers

Theoretical (kg) Practical.

Sodium bicarbonate 0.93 0.83 Up to 0.30 per cent cream acidity.

0.91. Beyond 0.30 per cent cream acidity

0.49Calcium hydroxide 0.41

Correct procedure for adding neutralizer

The neutralizer should never be dry when added, but dissolved in clean, potable water andproperly diluted, mixed with 10-15 times of its weight in water. The temperature of cream whenadding the neutralizer should be preferably is 29- 32 C. The cream acidity should be determinedto check to whether it has been correctly neutralized.

Role of carbon dioxide in neutralization of cream with sodium bicarbonate


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Fresh cream contains some dissolved carbon dioxide; acidic cream contain, more of it. Thecarbon dioxide reacts with sodium hydroxide during titration and shows a higher acidity test. Butthe carbon dioxide does not react with sodium bicarbonate neutralizer and consequently over-neutralization results.

Double neutralization wi th lime and soda.

The following sequence is recommended

First use lime neutralizer to bring down the cream acidity down to 0.3 to .4 %.Next use soda neutralizer to bring down the cream acidity to the desired level.The objectives of double neutralization are,

to avoid the intense effect on flavour of a large amount of any one neutralizer with high aciditycreamTo avoid production of excessive carbon dioxide by use of sodium bicarbonate with high acidcream.Pasteurization / vacreation of cream.Cooling and ageing of cream.Cream is cooled by lowering its temperature, and aged by holding it at this low temperature for afew hours. After pasteurization, the cream has to be cooled and then aged to make churning

possible. Cream will not churn until the butterfat on the fat globules has at least partially solidified:if insufficiently solid, due to improper cooling and ageing of the cream, the fat loss in the buttermilk will be excessive and the butter obtained will have an unsatisfactorily, weak body. UnderIndian conditions, the optimum temperature for the cooling and ageing of cream should preferablybe 5-10C. Cooling cream to abnormally low temperatures and ageing at near about the sameones, renders the fat globules firmer that they coalesce with each other during churning only withdifficulty, there by greatly prolonging the churning process. High cooling and ageing temperaturesof cream shortens the churning period, yields large fat losses in buttermilk and produce butter,which has a relatively soft body. Low cooling and ageing temperatures prolong the churningperiod, decrease fat losses, and produce a firm body that has a satisfactory standing up capacity.The ageing periods should be at least 2-4 hours, preferably 15-16 hours. During ageing,crystallization of fat in the fat globules should satisfactorily complete.

Shock cooling of warm cream with ice is not conducive to proper fat crystallization, since there isa subsequent temperature rise due to latent heat, consequent, inexhaustive churning and anunsatisfactory, weak bodied butter results.Ripening of cream:This refers to fermentation of cream with the help of desirable starter cultures.Objectives: 1. To produce butter with a pleasing pronounced characteristic flavour, aroma,uniformly from day to day.2.To obtain an exhaustive churning, i.e., a low fat loss in buttermilk.The butter starter culture containing lactic acid producers such as Lactococcus lactis subsp. lactisand Lactococcus lactis subsp. cremoris together with aroma (diacetyl) producers such asLacotcoccus lactis subsp. lactis biovar diacetylactis, Leuconostoc mesenteroides subsp.dextranicum or L. citrovorum, in correct proportions, is added to the standardized, pasteurized and

cooled (20-22C) cream at 0.5-2.0 per cent. After being thoroughly mixed, the cream is incubatedat 21for 15-16 hours. The typical flavour of butter from ripened cream is mainly the effect ofdiacetyl, and to a smaller extent, of acetic acid and propionic acids. There is no dactyl in sweetcream. The normal diacetyl content of ripened cream butter is on average 2.5 PPM and very rarelyover 4 PPM.Synthetic flavours:Cream ripening is expensive and time consuming and exacting. Further, most flavors enter intothe buttermilk and wash water, and are loss to the butter, Hence the use of starter, starter distillate or synthetic flavours, which are mixed with sweet-cream butter during the workingprocess to impart the characteristic flavour to the ripened cream butter or the finished product.


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One way of improving flavour is to increase the citric acid content of cream or milk beforefermenting begins.ChurningChurning of cream consists of agitation at suitable temperatures until the fat globules adhere,forming larger and larger masses and until a relatively complete separation of fat and serumoccurs. The object of churning is to produce butter from cream. The fat exists in the form ofemulsion i.e. a continuous phase. This emulsion is fairly stable. As long as it remains intact, there

is no formation of butter. The factors contributing towards the stability of this fat in skim milkemulsion are:Force of surface tension: this causes the fat globules in milk/ cream to retain their individuality andprevent butter formation.Phenomenon of adsorption: the surface layer of the fat globules contains an adsorbed,phospholipid protein complex, which resists deemulsion.Electric charge: the fat globules have negative charge and repel each other. The chargedecreases as the cream acidity increases.Viscosity: increased viscosity retards churning.A greater concentration of fat globules in cream promotes a more profuse and rapid coalescenceand aggregation than milk.

Churning of cream

Good churnability refers to clear breaking stage churning until the grains of butter are of thecorrect size. Exhaustiveness of churning - refers to fat losses in buttermilk, satisfactory washingand optimum churning period.

Factors influencing churnability of cream and body of fat

Chemical composition of fat: an increase in the proportion of soft fat shortens the churning period,diminishes the firmness of butter and increases the fat losses in butter milk and vice versa. Freshgreen succulent feeds increase the proportion of soft fat and dry hard feeds increase theproportion of hard fat.Size of the fat globes; the higher the proportion of the small sized fat globules, the longer thechurning time and the greater the fat loss in buttermilk and vice versa.

Viscosity of cream: the greater the viscosity of cream, the greater the churning period and viceversa.Temperature of cream at churning: Under Indian conditions the optimum churning temperatureranges from 9-11C. A higher churning temperature causes a shorter churning time, higher fatloss and a weak body in butter, which is difficult to wash and from which it is difficult to removecurd particles properly. A lower churning temperature prolongs the churning period.Fat percentage of cream. The higher the percentage of cream, the lower the churning period.The fat percentage under Indian conditions will be 40 for cow milk and 35 for buffalo milk.Acidity of cream: according to Hunziker, acid cream churns more rapidly and exhaustively thansweet cream. However Mc Dowel believes that the reverse is the case.Load off churn: the butter churn should be filled with one-half to one third of its total capacity withcream. Overloading prolongs churning time, while under loading reduces total capacity of the

churn.Nature of agitation: this is influenced by he size, type, and RPM of the churn, and affects thechurning period.Pre-churning ageing period. Refers to cooling and ageing of cream.Churning:

Preparation of churn: a new churn requires careful pre-treatment before use. An old churnrequires proper sanitation and cooling, to render it clean.Filling the cream into the churn: the amount of cream filled should be slightly below the ratedcapacity.


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Addition of butter colour: this is done to maintain the uniformity of yellow colour in butterthroughout the year for consumer satisfaction. The amount of standard color added varies from 0to 250 ml or more per 100 kg of butterfat. The butter colour should preferably be added to thecream in the churn.

Butter colour should have the following properties: it should be harmless, free from off flavours,concentrated, permanent, and oil soluble. Butter colours are of following types:Vegetable origin; annatto and carotene. Annatto is obtained from the seeds of the annato plant(Bixa orellana) carotene is extracted from carrots and other carotene rich vegetable matter. Its usegrowing for it increases vitamin A potency.Mineral origin. harmless oil soluble coal tar dyes. Examples: yellow AB ( benzene Azo - naphthyl-amine), Yellow OB( ortho toluene Azo--naphthyl amine).Operating the churn:After initially rotating the churn for 5 10 min., the liberated gas is removed once or twice byopening the churn vent. Then the cream sample is drawn for the fat test. During the churningprocess there is invariably a rise in temperature from 1-3C. Churning is accompanied by foaming.Then comes the breaking stage. When the cream breaks away from the spyglass, whichbecomes clear. At this stage the fat in the skim milk emulsion breaks and very small butter

granules of the size of pin heads make their appearance, it is sometimes necessary especially inthe tropics, to add break water at this stage to reduce the temperature of churn contents, andthereby control the body of the butter. The amount and temperature of breakwater depends on thetemperate reduction required. After the breaking the churning is continued until the butter grainsare of the desired size (viz., pea size in large churns). In the tropics, addition of breakwater canbe avoided by providing an air-conditioned butter making room and /or chill water spray over thebutter churn.Factors affecting fat loss in buttermilk

Fat percentage of cream: Lower the fat percentage of cream, the lower the fat percentage inbutter milk, but the greater is the percent total fat loss in buttermilk, vice versaSize of fat globules. the greater the proportion of small sized fat globules, the greater the fat loss,and vice versa

Acidity of cream at churning. According to Hunziker, sour cream causes a lower fat loss thansweet cream; but according to Mc Dowell, the reverse is true.Physical properties of fat: the softer the fat, the more the fat loss and vice versa.Condition of cooling and ageing: insufficient cooling and ageing i.e. improper crystallizationcauses more fat loss and vice versaConditions of churn: overloading, gross under loading and under churning all a cause a greaterfat loss in butter milk.

Washing :When the cream has been churned the churn is stopped in the proper position, a drain-plug fixedand the buttermilk removed thorough sieve.The purpose of washing is

Remove all loose buttermilk adhering to butter grains so as to reduce the curd content of butter,thereby improving its keeping quality.To correct defects in the firmness of butter by proper adjustment of wash water temperatures, andTo decease the intensity of certain off flavoursAfter buttermilk has been drained chilled water is added to the butter grains in the churn. Thetemperature of water is usually1-2C lower than the churning temperature of cream and anamount equal to the quantity of buttermilk removed. Normally one wash is enough for goodquality butter. The quality of water should be physically clean and bacteriologically and chemicallysafe. It is better to use freshly pasteurized and cooled water.Salting


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Refers to addition of salt to butter.

To improve keeping qualityTo enhance the taste.To increase overrun. Salt is usually added at the rate of 2.0-2.5 % of the butterfat. Excessive saltdamages the quality of butter.The calculated amount of salt may be added to butter either by sprinkling the powder salt over thebutter surface during working or it may be wetted in the least amount of potable water and thensprinkled over the butter during working. The salt is added in the form of a saturated solution ofbrine.

Specifi cations of butter salt

The salt should be a coarse grained and free from lump. It should pass completely through and ISsieve-85 (aperture 842 microns). 99.5 99.85 % sodium chloride on dry matter. Bacterial countsless than 10/kg. Completely soluble. High rate of solution. Negligible sediment.Working:

This refers to the kneading of butter,

Objectives:

To completely dissolve, uniformly distribute and properly incorporate the salt.To expel buttermilk and to control the moisture content of butter,To fully incorporate the added makeup water in butter.To bring the butter grains together into a compact mass for convenient handling and packaging.During working, the moisture in butter is reduced to droplets of microscopic size, which are mostlysterile.

The working should be continued until the butter has a compact body, closely-knit grain, a toughwaxy texture, and an even distribution of salt and moisture. Indicator paper develops a colouredspot if free moisture is present. Both over working and under working should be avoided; the

overworking damages the body and texture of butter and under working produces leaky butter.Working increases the air content of butter. Normally worked butter has an air-content of 0.5-10ml/100 g. The air content of butter is important because it affects I) the density of butter ii) itsmicrobial spoilage; and iii) its oxidative spoilage.

Packaging and storage of butter

Objectives o f packaging

To offer protection against contamination and damageTo protect the butter against loss in weight and degradationTo provide ease and safety of transport;To provide a convenient form of disposal;To identify the contents and increase sales appeals, appearance etc.The packaging materials includeWood or timber, parchment paper/substitutes, aluminum foil /laminates, tin-plates cans etc. Tinplate cans are advantageous in tropical countries not only in preventing melted butter fromescaping in hot weather but also in preventing absorption of foreign flavours. The packaging maybe hand moulding and wrapping; or it may be mechanical moulding, patting, and wrapping.The standard butter-packaging machine is automatic or semi automatic. The weight of thepackaged butter pats should be checked regularly as they come out of the machine.


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Vacuum packaging of butter in tin cans does not significantly improve the keeping quality,because the oxygen enclosed in the butter or dissolved in the fat is only partially removed.Canned butter is not sterile.

Storage:

The temperature of cold storage of butter ranges from 23 to 29C. There is invariably someflavour deterioration of butter during commercial cold storage, thus a fishy off flavour develops in

salted acid butter. Bacteriological deterioration plays a negligible part, while chemical degradationplays a leading one.

Shrinkage of butter during storage of patted butter:Shrinkage refers to loss in weight and is caused mainly by evaporation of moisture from the butterpat. The extent of shrinkage depends on

Type of wrapper. Moisture proof / greaseproof wrappers cause less shrinkage than other types.Condition of moisture in butter. The greater the quantity of free moisture in butter, the greater theshrinkage and vice versa.Size of pat: the smaller the pat, the greater the shrinkage and vice versaTemperature of storage: the higher the temperature of storage the greater the shrinkage and viceversa

Relative humidity of storage air: the higher the humidity, the lower the shrinkage, and vice versaPeriod of storage: the longer the period, the greater the shrinkage ad vice versaKeeping quality of butter:

The factors affecting the keeping quality are

Temperature of storage:Copper and iron content the higher the content the lower theSalt content of butter keeping quality.Acidity content of butterCurd content of butterAir content of butter.Raw or pasteurized cream: pasteurization of cream increases the keeping quality.

The method of packaging: sanitized high quality packaging materials and sanitary methods ofpackaging increase the keeping quality and vice versaExposure to light lowers the keeping qualitySweet cream /unsalted butter has the maximum and acid cream /salted butter the minimumkeeping quality under commercial cold storage.Over run in butter

Over run may be defined as the increase in the amount of butter made from a given amount of fat.It is usually expressed as a percentage. Over run is caused by the presence of moisture, curd, saltetc., in butter. It is a source of profit to the butter maker and helps to check the efficiency offactory operations

Types:

Theoretical over run:Maximum obtainable, viz.25%. Since the minimum legal fat content of butter is 80%, themaximum amount of butter that can be made from 100 kg of fat are 100/80x100=125kg. Thisgives an overrun of 25 %, which is not obtainable in actual practice.

Actual over run:On the basis of fat actually bought and butter made there from.Factors influencing over run:Inaccuracy in weight, fat test of milk, cream or butter:Fat losses in skim milk or buttermilk:Mechanical fat losses


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Unavoidable fluctuations in the fat content of butterWeight allowances in butter packs or cream or butterHandling losses etc.Formula for calculation of overrun

% OR = B- F X 100

F

WhereOR= overrun in butterB= butter made(kg)F= fat in churn (kg).

Yield of butter

This is calculated by the formula:

F X (100+%OR)Y=

100WhereY =yield of butter (kg)

F =fat content of cream. (Kg)

%OR = Percentage over run in butter (Ave. 20-22).

Theories of churning:

They are three main theories on the churning of cream in to butter. Viz.Fisher and Hookers phase reversal theory

Rahns foam theory

Kings modern theory.

Fisher and Hookers Phase Reversal Theory:According to this theory, churning is a process of phase reversal, i.e. changing an oil-in-water typeemulsion to a water-in-oil type emulsion such as butter. Agitation of cream in the churningprocess causes coalescence and clumping of fat globules until eventually the ratio of the surfacearea to the volume of fat units becomes so small that it can no longer contain all the buttermilk instable form. The fat-in-water emulsion then suddenly breaks, yielding butter grains and freebuttermilk.Drawback:Butter is not true water in fat emulsion. Microscopic studies reveal that a proportion of fat globulesin butte is still intact in the worked butter.Rahns Foam Theory:According to this theory, the presence of foam/froth is essential for churning. It also postulatesthat there is a foam producing substance present in cream, which gradually solidifies as thecream, or milk is agitated. Foam is created during the churning period. The fat globules due to


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surface tension effect tend to concentrate and clump on the foam bubbles. The foam producingsubstance assumes a solid character and the foam collapses. The fat globules then coalesce andbutter is formed.Drawbacks:Foam formation is not required in some continuous butter making processes.Kings Modern Theory:According to this theory,

In cooled cream at churning temperature, the fat is present as clusters of fat globules; and withineach globule it is present partly in liquid and partly in solid form.Churning breaks up the cluster and cause foam/ froth formation. The globules becomeconcentrated to some extent in the film around the air bubbles in the foam and are thus broughtinto close contact with each other.The movement of the globules over one another in the foam film and the direct concussionbetween them causes a gradual wearing away of the emulsion protecting surface layer of thephospholipid protein complex. The globules then adhere together to form larger and largerparticles. Eventually these particles become visible as butter grains. As the granules form , theyenclose some of the air from the foam. The fat in the granules is still mainly in globular form.The working of butter grains cause the globules to move over one another, under the effect offriction and pressure, some of them yield up a portion of liquid fat. Others are broken up during

working. Finally there is enough free liquid fat present to enclose all the water droplets, airbubbles and intact fat globules.Continuous butter making (CBM)

A number of types of continuous butter making machines have been developed for commercialuse.

Advantages of CBM:

More economical due to lower capital cost, lower running cost (reduced power, labour,refrigeration, steam, detergent etc.,).Reduced floor space, no expensive foundations to prepare, no time loss for fat crystallization, lessin butter wastage, etc.,More hygienic due to its being a closed system, free from air borne contamination.Disadvantages:

Lack of uniformity on the quality.Difficulty in grading and analysis.Basic principles:

The continuous methods of butter production developed since 1935 may be divided into threemain groups.

Groups I:

Fritz process or churning process: this involves the use of high-speed beaters to destabilize the fat

emulsion in the chilled cream, and thus cause the formation of grains of butter in matter ofseconds. The buttermilk is drained away and the resulting grains worked in a kneading sectionprior to extrusion.

Group II:

Alfa-Laval process or the concentration and phase reversal process. This involves a systemwhereby cream of 30-40 per cent fat is concentrated in a special cream separator to 80-82% fat.After standardization, the concentrated cream or butter mix is subjected to combined cooling and


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mechanical action, which causes phase reversal and the formation of butter, followed by itsexpulsion from the machine.

Group III:

Cherry Burrell process which again involves the concentration of 30-40 % cream. Duringconcentration, the emulsion is broken and the fat, water, and salt content are standardized. Thisis followed by re-emulsification, cooling working, and finally extrusion.

Defects in but ter, their causes, and prevention

Defects in butter may arise due to low quality milk or cream, and faulty method of manufactureand storage of butter. The common defects in butter, their causes, and prevention are givenbelow.

Name of the defect Causes Prevention.

Flavour

Acid /high acid /sour.

Using acid cream

Under neutralization.

Using sweet cream

Optimum neutralizationof cream.

Alkaline/neutralizer over neutralization ofcream

Optimum neutralization

Bitter Intake of bitter weedsby milch animals.

Lipase activity duringraw cream separation.

Growth of proteolyticbacteria in cream.

Eradication of offendingweeds

Checking lipase activityby avoiding the dangerzone during raw creamseparation.

Cheesy Growth of proteolyticbacteria leading tocasein breakdown

Storage of cream at5Cor below to checkbacterial growth.

Cooked Overheating of creamduring pasteurization.

Optimum heating ofcream duringpasteurisation.

Feed and weed Feeding of milk taintingfeeds and weeds within

three hours beforemilking.

Feeding of milk taintingfeeds and weeds soon

after milking.

Fishy High acid salted butterin the presence ofappreciable amounts ofcopper and / or ironcontent undercommercial coldstorage.

Unsalted sweet creambutter under commercialcold storage.


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Flat low diacetyl content inbutter

Low salt content inbutter

Excessive washing ofbutter

Adequate ripening ofcream before churning.

Correct salt content ofbutter.

Optimum washing ofbutter.

Rancid. Fat hydrolysis due tolipase action in milk orcream.

Inactivating lipase byproper pasteurization ofmilk or cream.

Oxidized/oily/metallic/tallowy

Fat oxidized due todirect contact of milk /cream butter withcopper or iron,exposure of theseproducts to sunlightetc.,

Storage ofmilk/cream/butter inproperly tined oraluminum alloy orstainless steel vessels,Vacuum pasteurizationof cream.

Stale Cream or poor qualityheld too long beforechurning.

Butter stored atinsufficient lowtemperature for longperiods.

Avoiding storage ofcream during churning.

Correct temperature forstorage of butter.

Yeasty Using old, yeasty creamfor churning.

Using fresh, sweetcream for churning.

b) Body and texturedefects

Crumbly Under working of butter

Seasonal changes in fatcomposition

Sudden chilling of buttersoon after production.

Adequate working ofbutter

Controlled coolingageing churning andwashing temperatures.

Avoiding hock cooling ofbutter soon afterproduction.

Greasy Overworking of butter

Excessively hightemperature of washwater.

Adequate working of

butter

Correct wash watertemperature.

Gummy High proportion of highmelting point fats.

Avoiding feedscontaining high meltingpint fats

Leaky Under working of butter

Excessively high

Adequate working ofbutter correct churning


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churning temperature ofcream

Over churning of butter

Incorrect cooling ofageing of cream.

Excessively hightemperature of washwater.

temperature of cream

Optimum churning ofbutter

Correct cooling andageing of butter

Correct temperature ofwash water.

Mealy or grainy Incorrect neutralizationof high acid cream withlime

Oiling off of fat duringbutter making.

Correct neutralization ofhigh acid cream withlime.

Avoiding oiling off of fatduring butter making.

Spongy/weak. Inadequate cling andageing of cream.

Churning cream at toohigh temperature

High proportion of lowmelting point fats.

Adequate cooling ofageing of cream.

Churning cream atoptimum temperature

Adjusting churningconditions to take careof high proportion of lowmelting point fats.

Sticky Over working of butter Adequate working ofbutter.

Gritty n-dissolved coarse saltin butter

Incorrect salting ofbutter

Proper grinding of butter

Correct salting of butter.

c) Colour

Mottled Inadequate washing ofbutter grains

Improper incorporationof salt in butter

Inadequate working ofbutter.

Adequate washing ofbutter grains.

Proper incorporation ofsalt in butter.

Adequate working ofbutter.

Streaky/wavy Uneven working ofbutter.

Incomplete working oftwo or more lots ofbutter.

Even working of butter

Complete working oftwo or more lots ofbutter

Dull /pale, Overworking of butter. Adequate working ofbutter.


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Uses of butter

Direct consumption .In the preparation of sauces.As a cooking mediumIn the baking and confectionery industries.In the manufacture of Ice cream, butter oil and ghee.In the production of reconstituted milk.

GHEE

Ghee may be defined as clarified butterfat prepared chiefly from cow or buffalo milk. (Toclarify means to make clear a liquid or something liquefied, by removing unwanted solid matter orimpurities.)

According to the PFA (1976), ghee is the pure clarified fat derived solely from milk or from desi(cooking) butter or from cream to which no colouring matter is added.

Chemical composition of ghee

Characteristics Requirements

Cow Buffalo

Milk fat 99 to 99.5 per cent

Moisture Not more than 0.5 per cent

Unsaponifiable matter

a) Carotene (g/g.) 3.2-7.4 -

b) Vit.A (I.U./g) 19-34 17-38

c) Tocopherol (g/g.) 26-48 18-37

Free fatty acids (%oleic)

Max. 2.8 (agmark)

Charred casein, salts ofcopper and iron, etc.,

Traces

Physico-chemical constants:Ghee is characterized by certain physico-chemical properties, which show some natural

variations depending on such factors as, method of manufacture, age and condition of the sample,species, breed, individuality and animals stage of lactation, season of the year, region of thecountry, feed of the animal etc., Some of the important analytical constants or standards of mixedghee produced under standard conditions are given below:

1) Melting and solidifying points:


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The melting point varies from 28C to 44C, while the solidifying point varies from 28C to15C. (As ghee fat is of a mixture of glycerides, it does not have a sharp melting or solidifyingpoint).

2) Specific gravity:

This varies from 0.93 0.94.

3) Refractive index:

The Butyro-Refractometer (B.R), reading (at 40C ) varies from 40-45.

4) Reichert-Meissl (RM) Value:

This is also known as Reichert value, and this should be normally not less than 28. However,ghee from cottonseed feeding areas, the limit is 20.

5) Polenske value (P.V):

This should be normally not more than 2 (except for cotton-seed feeding areas, wherethe limit is 1.5)

6) Saponification value:

This should be normally not less than 220.7) Iodine value:

This should normally vary from 26 to 38.

(Cotton tract refers to the areas in the states where cottonseeds are extensively fed to the cattleand so notified by the state government concerned.)

Methods of preparation:

Ghee can be prepared by various methods, which are as follows:

Country/Desi method

Creamery butter method

Pre-stratification method

Direct cream method

Continuous method

Desi Method:

Fresh or accumulated over a few days, makkhan (butter) is taken in a suitable open mud-potor metallic vessel, and heated and stirred on a low fire to drive out the moisture. When practicallyall the moisture has been removed, a stage judged by experience, further heating is stopped andthe vessel removed from the fire. On cooling, when the residue has settled down, the clear fat isdecanted into suitable containers.

Merits:Desirable flavour,

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