Milk and Milk Products_Food Biotechnology.pptx

Milk and Milk Products_Food Biotechnology

1. MILK AND MILK PRODUCTS

2. DEFINITION AND COMPOSITION OF MILK The normal secretion of the mammary glands of all mammals. Milk is the lacteal and physiological secretions of mammary glands obtained from healthy cows or buffaloes (excluding fifteen days before and five days after parturition)

3. and contains at least 3.5% fat and 8.5 solids-non fat. Milk is a complete food for the new born. High density of nutritious components .

4. The basic composition of milk regardless of the source remains the same: Water 87.1% Carbohydrate 4.8% Protein 3.8% Fat 3.5% Minerals 0.8%

5. MILK CARBOHYDRATE Lactose – main CHO Low solubility, may precipitate out as grainy substance during heat treatments Converts to lactic acid with souring or fermentation – lactose stays in whey Part of milk-solids-non fat Less sweet than sucrose

6. MILK FAT 3-4% for whole milk, varies according to breed Primarily triglycerides, then phospholipids, sterols Mix of unsaturated, monounsaturated and polyunsaturated fatty acids High level of short chain – contribute to milk flavor and low melting point of butter Fat globules less dense than water  less stable “Creaming” process – fat rises to the top

7. MILK PROTEINS CASEINS Casein is a complex protein that makes up 80 percent of the protein in milk. The casein micelle makes many of the functions of casein possible, such as ease of digestion and the growth and development of the young. It is also necessary for cheese-making and other food production technologies. Can be separated by acidification Rennin- enzyme also precipitates casein  clotting, curdling when milk sours

8. MILK WHEY When special enzymes are added to the milk, it separates into curds (which are used to make cheese) and liquid whey. The whey protein is then pasteurized and dried so it can be used as a key ingredient in some drink mixes, protein bars and other foods. Whey protein is generally safe and can help to build muscle and strength, lose weight, reduces appetite and boosts metabolism. Enzymes – lipase, protease, alkaline phosphatase

9. MILK VITAMINS Cow milk contains all water soluble B vitamins and is an excellent source of riboflavin, pantothenic acid, folates and vitamin B 12 . Moreover, bioavailability of B vitamins in cow milk is good. It is high in vitamin A and some D and contains small amounts of vitamin C. Milk Vitamins play an important role in intermediary metabolism as co-factors in numerous enzymatic reactions or in non- enzymatic physiological functions such as the visual process (vitamin A), as antioxidants (carotenoids, vitamins E, C and riboflavin) and in regulation of calcium metabolism (vitamin D).

10. MILK MINERALS Calcium Phosphorus Magnesium Potassium Sodium Chloride Sulfur

11. MILK PIGMENTS The vegetable colouring pigments present in milk include carotene and xanthophyll, grouped together as carotenoids. Beta-carotene which is found in the grass where the cows graze on. Carotenoid is a precursor of vitamin-A which gets converted into enterocytes and hepatocytes of animals.

12. FLAVOR OF MILK Mouth feel due to emulsified fat, colloidally dispersed proteins, lactose and milk salts. Fresh milk contains acetone, acetaldehyde, methyl ketones and short chain fatty acids to provide aroma. Normally milk has a mild sweet flavor. Heat processing changes milk flavor. Milk flavor is affected by physical condition of cow and composition of the feeds being offered to animals.

13. OFF FLAVORS Off-flavors commonly found in milk can be classified in three basic categories - the ABC's of off-flavor development. Absorbed - feedy, barny, cowy, unclean, weedy, and musty. Main cause: pasture weeds Old or moldy feeds provide rancid or bitter flavors. Oxidation of fat: oxidized phospholipids provide fishy odors.

14. PA S TEURIZA T ION Heating every particle of milk to a particular temperature in order to destroy most of the pathogenic microorganisms and deleterious enzymes present in milk and to cool down milk immediately at 4 C. Destroys lipase which catalyzes hydrolytic rancidity. Process is time/temperature dependent.

15. TIME/TEMPERATURES of PASTEURIZATION Use high temperature, short time (HTST) 162 F, 71-72 C for 15 seconds Low temperature, longer time (LTLT), 145 F, 63-64 C for 30 minutes Ultra-high temperature (UHT), 280 F, 135-150 C for 2-4 sec. May develop cooked flavor.

16. STERILIZATION Only occurs with high temperatures 121°C (250°F) for 15-30 minutes. Can be aseptically packaged; no refrigeration until opened.

17. HOMOGENIZATION Prevents creaming; maintains more uniform composition, optional process. Mechanically reduces fat globule size, increases number of fat globules and permanently emulsifies fat globules. Reduces fat globules from 3-20µm to <2µm.

18. FORTIFICATION Whole milk - optional addition of Vit. A & D Low fat milk, non-fat, low-fat chocolate - must be fortified for Vit. A. Addition of Vit. D optional but routinely practiced. To increase viscosity, appearance, and nutritive value of low fat milk, non-fat milk solids may be added.

19. VARIETIES OF MILK

20. VARIETIES OF MILK: Fluid Milk Must be free of pathogenic bacteria. Fat content and % of MSNF subject to food regulations. Flavored – same nutrients as milk to which flavor added. Certified milk – limited distribution due to cost and sanitary standards very high. Eggnog- mixture of dairy ingredients (cream, milk) egg yolk containing ingredients, nutritive carbohydrate sweeteners.

21. Canned whole milk – homogenized, sterilized and canned aseptically. Frozen whole milk – homogenized, pasteurized, fat separates when thawed and protein denatured by freezing Skim or non-fat – as much fat as possible removed, min i mum of M S N F , f o rti f ied wit h v i tami n A. O p t i o na l : vitamin D, emulsifiers, stabilizers. Low-fat milk – some fat removed, named according to fat remaining, minimum MSNF, fortified with Vit. A. Optional: Vit. D, emulsifiers, stabilizers.

22. CONCENTRATED MILKS: EVAPORATED MILK Concentrated through process of evaporation. Evaporated in a vacuum chamber. Whole or nonfat – 60% of H 2 O is removed. Homogenized, fortified, canned and sterilized. Increasingly less stable with progression of concentration and heat may coagulate . Reconstituted by 1:1 ratio.

23. CONDENSED MILK Similar in content of evaporated milk and no sugar is added. NOT sterilized. Perishable at temperatures above 45 F.

24. SWEETENED CONDENSED MILK Concentrated whole or non-fat milk. 60% of H 2 O is removed. Sweetened with sucrose or dextrose prior to concentration. 40-45% sugar level, may cause grittiness. Pasteurized, not sterilized due to high concentration of sugar.

25. DRIED MILK Processed from whole or nonfat milk (more common). Condensed and 2/3 of H 2 O is removed. Sprayed into heated vacuum chamber and contains less than 5% moisture level. Most non-fat milk is fortified. “Instant” or “agglomerated” – some moisture added back and are pourable, dispersible, in cold H 2 O. May also dried as buttermilk and whey.

26. CULTURED/FERMENTED MILK & MILK PRODUCTS Cultured products fermented by addition of bacterial cultures viz. Streptococci and Lactobacilli Ferment lactose to lactic acid; create low pH to coagulate casein. Acidified products – souring milk with acid, with or without microorganisms. Cultured and acidified products contain different amounts of lactic acid of different flavors.

27. BUTTERMILK Traditionally liquid left after churning butter, differs from non-fat milk due to content of phospholipids and proteins. Cultured buttermilk – pasteurized low fat or non-fat milk with Lactobacilli and Streptococci. Acidified buttermilk – lactic acid producing bacteria, however, not compulsory. Smooth cultured flavor, high acid content and useful in cooking.

28. SOUR CREAM Traditionally heavy cream soured. Pasteurized, homogenized and fresh light cream. Coagulated similar to buttermilk. Flavors and stabilizers are added. Proteolytic bacterial enzyme activity may cause bitter flavor after 3-4 weeks.

29. YOGURT Cultured pasteurized dairy product with Lactobacillus bulgaricus and Streptococcus thermophiles. Sealed for live and active bacteria; at least 100 million bacteria/gram at time of manufacture. Yogurt with viable strains of bacteria eaten in sufficient quantities some will survive passage through stomach and release lactase in the intestine.

30. OTHER PRODUCTS Acidophilus Milk - pasteurized low-fat or nonfat milk with Lactobacillus acidophilus . Added bacteria can live in intestine and produce number of B-vitamins. Reduced Lactose Milk - pasteurized milk treated with lactase and sweeter than regular milk. Kefir– fermented dairy products, kefir grain and beneficial bacteria are added to milk. Koumiss – milk heated before fermentation and ferments to yield soft curd with yeasty sour curd with mild alcoholic flavor.

31. MILK SUBSTITUTES Imitation milk – combination of several non-dairy ingredients and nutritionally inferior to cow milk. Substitute milk – nutritionally equivalent; reduced calories or fat, usually milk derivatives (casein, casein salts, whey). Filled milk – substitute milk with milk fat replaced with vegetable oil.

32. THANKS!