Milk composition

Milk composition and Dairy products and economics

1. Milk composition Dairy products and economics AKP தோழா M.S. UNIVERISTY TIRUNELVELI.

2. Milk It is the secretion of mammary glands in human and animals after labour . It is the only food for newborn for a long period till weaning time. Before birth the fetus receives its nutrition through the placenta. Milk secretion is stimulated by Prolactin . Milk flow is decreased by Estrogen and Progesterone while increased by Thyroxin . Initiation of lactation may result from sudden removal of the placenta and other factors. Oxytocin (posterior pituitary hormone) responsible for milk ejection.

3. C omposition of milk Water is the principal constituent of milk. Milk provides essential nutrients and is an important sources of dietary energy, high quality proteins and fats . Milk consist of nutrients like calcium,magnesium,selenium,riboflavin,vitamin B12 and pantothenic acid. Milk and milk products are nutrient dense foods and their consumption can add diversity to plant based diets. Animal milk can play an important role in the diets of children in populations with very low fat intakes and limited access to other animal source foods. The colour,flavour and composition of milk depends on the species of dairy animal, its breed, age and diet, along with the stage of lactation, parity (number of parturition),farming system, physical environment.

4. Milk composition in dairy animals Cow milk Water -87% Fat – 3-4% Protein – 3.5% Lactose - 5% Minerals -0.8% Yak milk Water – 83% Fat – 5.5 to 9% Protein – 4 to 5.9% Solid content – 18%

5. Equine milk ( Horse and Donkey milk ) Water – 91% Fat – 1.9% Protein – 2.5% (particularly caseins ) Lactose – 6.3% (rich ) Minerals – 0.3% Camel milk Water – 86.5% Fat – 4% Protein – 3.6% Lactose – 5% minerals – 0.4% Human milk Water – 87.6% Fat – 4% Protein – 1.2% Lactose – 7% Minerals – 0.4%

6. Goat milk W ater – 87% Fat – 4% Protein – 3.6% Lactose- 4.5% Minerals – 0.9% Sheep milk Water – 80% Fat – 8% Protein – 5.6% Lactose – 4.8% Minerals - 0.9% Buffalo milk water – 82% minerals – 0.8% protein – 4.5% lactose – 4.8% fat – 7 to9% very high fat content

7. Milk is formed of Water: form 87%. 2) Solids: form 13%. Organic constituents of milk. 1.Protein 2.Lipid. 3.Carbohydrate . Inorganic constituents of milk: Minerals. Vitamins.

8. Organic Constituents of Milk 1- Protein: Milk protein less in human than in cow's milk. All milk protein synthesized in the mammary gland. Milk protein of high coefficient digestibility (85 – 95 %) Characterized by: 1. Protein of high biological value as: It contains all essential amino acids. Easily digested. Easily absorbed. Easily metabolized. 2.It Contain moderate amount of non essential amino acids to decrease stress on body cells. 3.Essential to keep positive nitrogen balance (nitrogen intake more than nitrogen output). 4 . Essential to maintain growth of newborn .

9. Types of Milk Proteins are: 1.Casein. 2.Lactalbumin. 3.Lactglobulin. 4.Milk enzymes. 1) Casein It is the main and most dominant milk protein . It represents 25% in human's milk and 83% in cow's milk. It is a compound protein ( Phospho -protein) of high biological value. The high phosphate content of casein allows it to associate with calcium and form calcium phosphate salts. Casein contains 0.7% phosphorou s and 0.7% sulpher . Casein is the only milk protein that not coagulated on boiling . The net charge of milk protein is negative charge, so protein molecules remain separated from each others due to repulsion forces.

10. 2. Lactalbumin Represent 87% of whey protein. Protein precipitation by full saturation with ammonium sulphate . Rich in cystein and cystin so give + ve result with sulpher test. Simple protein. Soluble protein. Easily digested .

11. 3- Lactglobulin Represent 13% of whey protein. Protein precipitation by half saturation with ammonium sulphate solution. Rich in cystein and cystin so give + ve result with sulpher test. Simple protein. Soluble protein. Easily digested . Consists of two fractions: α Lactalbumin 32% of whey protein. β lactglobulin 55% of whey protein.

12. 4- Milk enzymes : Catalase. Peroxidase. Xanthin oxidase. Alkaline phosphatase. Amylase. Lipase. Aldehyde oxidase.

13. 2- Lipids Human's and cow's milk contain the same amount 3.5 gm /dl but buffalo's milk is a little higher 7 gm /dl . Easily separated on standing. Responsible for white color of milk It consists mainly of triacylglycerol distributed as coarse emulsion which contains oleic, myristic , palmitic and stearic fatty acids . Also contain small amounts of: phospholipids 0.1 % Cholesterol 0.01 %. 3- Carbohydrates Lactose (milk sugar ) is the only carbohydrate of milk. It is a reducing disaccharide consists of glucose and galactose . Human's milk contains 7% lactose while cow's milk contains 5% lactose . Lactose may be excreted in urine during last third of pregnancy physiologically so it should be differentiated from glucose by osazon test .

14. Inorganic constituents of milk 1- Minerals: Human milk contain less mineral elements (0.4%) than cow's milk (0.8%). Milk rich in Ca and P which are present in their proper ratio for absorption (2:1) in human milk while in cow's milk (1:2 ) Ca and P are essential for: Growth of bone and teeth. Stability of casein. Milk contain adequate amount of Na, K, Mg. Human milk contains Na:K (1:2) which is suitable for the optimal growth of newborn.

15. 2- Vitamins: Milk is deficient in: Vitamin C . ( form – Ascorbic acid 1.5mg in 100ml cow milk) Vitamin D. Vitamin K . Milk contain adequate amount of vitamin B complex which are sufficient for first week of life e.g : Pantothenic acid. Riboflavin (gives the whey the greenish tint in sunlight )

16. milks 9 essential nutrients Calcium = strong bones Vitamin D = calcium absorption Riboflavin = energy Phosphorus = strong bones Protein = lean muscle Potassium = fluid balance & blood pressure Vitamin A = good vision & skin health Vitamin B12 = red blood cell formation Niaci n = energy

17. Factors affecting milk composition Species: Milk protein: Rabbit's milk 10% while cow' milk 3.7%. Milk fat: Cow's milk 3.5% while buffaloe's milk 7%. Age: Old age decrease fat contents of milk. Seasonal variation: In winter increase in fat, protein and mineral contents of milk . Nutritional variation: Overfeeding has no effect on milk composition. Underfeeding decrease in milk volume and protein and lactose contents of milk while fat contents of milk increased. Infection of mammary gland: Mastitis decrease fat, lactose and casein contents of milk while whey protein and chloride ions increased .

18. Dairy Products Cultured Dairy Products - yoghurt Butter Cream Cheese Concentrated Dairy Products Frozen Dairy Products

19. 1.Yoghurt Dietetic Value Yoghurt contains HBV protein necessary for growth, therefore it is a suitable food for children & teenagers and necessary to repair cells, essential for those recovering from illness Yoghurt is easily digested & is suitable for the elderly & convalescents Low-fat yoghurts are available & are particularly suitable for those on low-kilocalorie diets Economic Value Yoghurt can be used in a wide variety of dishes Yoghurt is available in a wide variety of flavours Yoghurt is relatively inexpensive to buy

20. Nutritive Value Nutrient Explanation Protein HBV Fat Saturated fat Amount depends on the type of milk : low fat, skimmed or full-fat Carbohydrate M ilk sugar lactose Can be i ntroduced by the addition of fruit & sweeteners Vitamins Fat – soluble: A & D Water – soluble: B1 thiamine, B2 riboflavin and niacin Minerals Calcium Small amounts of potassium & phosphorus Water V aries according to the fat content

21. Storing yoghurt Store in a refrigerator (below 5˚C) Use within the best before date Bio-yoghurts contain additional bacteria cultures such as lactobacillus casei , which manufacturers claim support the natural bacteria in the intestines & help to regulate digestion

22. Manufactured from milk .A water-in-oil emulsion Nutrient Explanation Protein A little High Biological Value protein in butter Fat A nimal fat (saturated fat) The fatty acid is called butyric acid Carbohydrates Trace amounts of lactose (milk sugar) Vitamins Fat-soluble vitamins A, D & E Minerals Traces of calcium & phosphorus S odium & chloride are added during production Water S mall amount - 14-16% 2 .Butter

23. Composition of Butter Protein Fat Carbohydrate Vitamins Minerals Water 1% 82% 0.5% 0.5% 2% 14% Must contain at least 80% fat to be called butter, by law. Production of Butter Cream(fat from milk) is pasteurised Cream is cooled & the fat hardens Cream is churned & the fat clumps together The liquid part, called buttermilk, is drained off Salt (1.5 %) is added The butter is packed for sale

24. Types of Butter Type Use 1. Salted: 2% salt is added Baking, table use 2. Unsalted: No salt added Low sodium diets, baking 3. Spreadable Butter: Churned for longer periods of time to allow for the fat globules to separate. This allows for a more spreadable product Sandwiches 4. Low-fat: Fat content reduced by 50% Low kilocalorie diets 5. Concentrated Butter: made up of 84% fat Sandwiches

25. 3 .Cream Milk is an oil-in-water emulsion. Cream is made from the fat of milk Nutrient Explanation Protein A pprox. 3% in cream HBV (animal protein) called casein Fat V arying quantities of saturated fat Depends on the type of cream Carbohydrate 2-4% called sugar lactose Vitamins Small amounts of B group vitamins A & D Minerals Calcium Water Varies according to type

26. Production of cream Milk is heated to 50°C It is then subjected to centrifugal force which separates the upper cream layer from the lower layer of skimmed milk The cream is heated using pasteurisation, sterilisation or ultra-heat treatment

27. Types of Cream Type of cream Use Half Cream 12% fat Pouring cream used in desserts Single Cream 18% fat P ouring cream used in desserts & sauces Double Cream 48% fat D ecoration of desserts Whipping Cream 35% fat Decoration of desserts UHT Cream 35% fat T rifles Sour Cream 18% fat In savoury dishes, e.g. sweet & sour Cream Alternatives: a) Crème Fraiche 30% fat A mixture of soured cream & yoghurt or buttermilk b) Fromage frais 13% fat Blend of soft cheeses c) Greek Yoghurt 10% fat T hick creamy yoghurt used instead of cream.

28. Classification Hard cheese Semi-hard cheese Soft cheese Processed cheese Cheddar Parmesan Swiss Stilton Gouda Cottage Brie Mozzarella Feta Cheese spread Cheese slices Smoked cheese Type Protein Fat Carb . Vitamins Minerals Water Hard Soft 26% 14% 33% 4% 0% 4% A, B2 A, B2 Calcium Calcium 37% 77% Composition of Cheese 4 .CHEESE

29. Nutritive Value Nutrient Explanation Protein HBV caseinogen Fat Saturated Hard cheese has more than soft cheese Carb . None in hard cheese, as they are lost during processing Small proportion in soft cheese of the disaccharide lactose present Vitamins Vitamin A, B2(riboflavin) & D No vitamin C Minerals Hard cheese is a very good source of calcium Water Hard cheese 33% Soft cheese 75%

30. Cheese-Making Milk is pasteurised Lactic acid bacteria is added .This changes lactose(milk sugar) to lactic acid 3. Milk is warmed to approximately 30°C 4. The enzyme rennet is added - milk protein, caseinogen converts to casein. The mixture is left for between 30-45 mins until casein turns to curds(solid) & whey(liquid) 5. Whey is drained off & the curds are chopped = Cottage cheese 6. Scalding = the curds are heated again (to 40°C) to shrink them further & the squeeze out more whey. 7. Cheddaring= the curds are cut into blocks & packed on top of each other to remove any remaining whey.

31. 8. 2% salt is added & more whey is drained off 9. The cheese is pressed into moulds 10. For protection, the cheese is sprayed with hot water & this forms a rind 11. The cheese is removed from moulds & wrapped in polythene bags, where it is left to ripen. Ripening time varies with the type of cheese, e.g. cheddar cheese is left to ripen for up to one year at 10°C. Cheddar cheese is produced at this point 12. The cheese is date-stamped, graded & packed

32. Dietetic Value of cheese Dietetic Value of cheese Rich in protein & calcium -essential for growth in children, adolescents, pregnant women & nursing mothers High-energy food - suitable for active people Cottage cheese (4% fat) and low-fat types for low-kilocalorie/low cholesterol/ weight-watching diets Lacks carbohydrates, should be eaten with foods rich in carbohydrate e.g. brown bread Economic Value Versatile, used in a wide range of dishes Economical - little or no waste Quick & convenient High energy, nutritious snack

33. Hot snack – cheese on toast Cold snack - sandwich Sauce making – cheese sauce Fillings - omelettes As dips & spreads Toppings - pizza Course at end of meal – cheese board Protein alternative Enhances nutritive value of a dish Culinary uses of cheese

34. 5.FROZEN Dairy products that have been prepared and stored at very low temperatures ICE CREAM Made from milk, cream, sugar and flavoring Generally has about 6-8 grams of fat REDUCED FAT has about 4-5 grams of fat LOWFAT has less than 3 grams of fat NONFAT has less than 0.5 grams of fat SHERBERT Made from milk, sugar and fruit juice FROZEN YOGURT Made from cultured dairy product, sugar & flavoring

35. 6.CONCENTRATED Dairy products that have had the water or liquids removed to increase the density Examples include: EVAPORATED MILK Has some water removed Can be reconstituted and used as fresh milk Available in cans SWEETENED CONDENSED MILK Has water removed and sweetener added Used most commonly in baking Cannot replace fresh milk or evaporated milk Available in cans NONFAT DRY MILK POWER Used by chefs because it does not spoil and it costs less than fresh milk Can be reconstituted and used as fresh milk Comes powdered in packets (boxes)… think hot cocoa