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MILK

MILK. Chapter 9. MILK. Unique Beverage In Existence for Thousands of Years Ancient Babylon Egypt India Provides Many Nutrients Complete Protein B Vitamins Vitamins A & D Calcium 80% Calcium Ingested Dairy Products Low In Vitamins C & E Iron

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MILK

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  1. MILK Chapter 9

  2. MILK Unique Beverage In Existence for Thousands of Years Ancient Babylon Egypt India • Provides Many Nutrients Complete Protein B Vitamins Vitamins A & D Calcium 80% Calcium IngestedDairy Products Low In Vitamins C & E Iron Complex CHO Fiber

  3. MILKFUNCTIONS IN FOODS • Ingredient Beverages Smoothies Milk Shakes Yogurt Drinks Eggnog Kefir CheeseYogurtSour CreamWhipped Cream • Derived from Milk Butter Milk Fat • Milk Components in Processed Foods Proteins Milk Sugar - Lactose

  4. MILKFUNCTIONS IN FOODS Milk Components in Processed Foods • Proteins Nutrients Emulsifiers & Stabilizers Gel • Milk Sugar Lactose Browning of Baked Goods Confectionary & Frozen Desserts • Contributions in Foods PRO Content Moisture Foaming Emulsification Texture Flavor

  5. Milk selection • Cow milk • Sheep and goat milk -Middle East, Europe • Camel milk - Iran, Afganistan • Reindeer milk - Lapland • Horse milk - Mongolia • Water buffalo milk - Phillipines, India, Italy • Yak and Zebu milk - China and Tibet

  6. Type of milk • Whole milk -3.25% fat • Reduced Fat - 2% fat • Low-Fat - 1% fat • Skim Milk (Fat-free milk) <0.5% fat • Chocolate Milk (1.5% liquid chocolate or 1% cocoa + 5% sugar) • Eggnog- eggs, nutmeg, cream, milk solids (6-8% of fat), rum extract, sugar, color, flavor additives • Carbonated Milk

  7. Type of milk • Filled milk -replacement of milk fat with a vegetable oils • Reduced-lactose milk - pasteurized milk treated with lactase. • Low-sodium-milk -produced by ion exchange method. Content of Na reduced from 120 mg to 6 mg per cup. • Goat, sheep and other animal milks • Soy Milk • Canned Milks -evaporated, sweetened condensed milk • Dry Milk NFDM, instant milk

  8. Creams and Cream Substitutes • Cream Fat Droplets Top Layer of Nonhomogenized Whole Milk 18-36% Milk Fat • Cream Substitutes Whipped Toppings Coffee Creamers Dry Mixes Imitation Sour Cream

  9. Cultured milk products • Buttermilk- milk cultured by adding Streptococcus lactis; flavor may be enhanced by other bacteria, butterfat granules, natural sweeteners, citric acid, artificial flavors and colors (<0.5% pH =4.6) • Cultured low-fat or acidified low-fat when fat content 0.5-2.0%. • Yogurt- Lactobacillus bulgaricus and streptococcus thermophilus, mixture is held at 42-46C, NFDM may be added, when desired consistency is reached the fermentation is stop usually by chilling. To create firmer texture gelatin or vegetable gums may be added. • Acidophilus milk - milk fermented with Lactobacillusacidophilus fermented until a slight curd is formed. • Kefir is a milk fermented at 23 C by Lactobacillus caucasius, and a yeast Saccharomyces kefir and Torula kefir . Kefir contains about 1% alcohol.

  10. Yogurt • Fermented Semi-Solid Milk • Active Yogurt Cultures • Ingredients Added to Yogurt • Definition 8.25 % MSNF & 0.5% Acid • Calorie Content Varies • Probiotics Live Beneficial Bacteria Prebiotics Nondigestible Food Ingredients FOS Support Growth of Probiotics

  11. Milk Safety • Milk unless pasteurized contains living microorganisms including pathogenic bacteria causing tuberculosis, diphteria, typhoid, scarlet fever, salmonelosis. • All pathogenic bacteria, yeast and molds are destroyed by a process called pasteurization and 95-99% of nonpathogenic bacteria. • Pasteurization is heating food product for a specific time at temperature below 100C • Pasteurization process also inactivates enzymes. • Activity of alkaline phosphatase is used as a marker of sufficient milk pasteurization.

  12. Physically milk is: • True solutions • Colloidal system • Dilute emulsion (oil in water) • In raw milk fat globules are between 2.5 and 5 mm in diameter • In homogenized milk fat globules are < 1 mm. • pH of fresh milk is about 6.6

  13. Contributors to milk color • Fat • Colloidally Dispersed Casein • Riboflavin – B2 Interfere w/ Light Transmission – Opaque • Carotene in Animal Feed Provides Yellowish Tinge Butter & Cream

  14. Proximate composition • Water 87% • Proteins 3.5% • Fat 3.5-3.7%; • Carbohydrates 4.9% (Lactose, glucose, galactose) • Vitamins niacin, riboflavin, thiamin, vit. B6, vit. A and D (depending on fortification) • Minerals Ca, P, Mg, K, Na, Cl. S. About 80% of Ca consumed by Americans is derived from dairy group products. • Enzymes: lipases, proteases, alkaline phosphatase, peroxidase • Color -fat, casein micelles, riboflavin -interfere with transmission of light -opaque, ivory color. Fat may contain carotenoids.

  15. MILK

  16. MILKCOMPOSITION

  17. Milk fat • Triglycerides 95-96%; up to 142 fatty acids. • Saturated fatty acids 66% • Unsaturated fatty acids 30% • Polyunsaturated fatty acids 4% • Phospholipids - 0.9-1.0% • Sterols - 0.22-0.41% • Cholesterol content per cup • whole milk 33 mg • 2% milk 18 mg • skim milk 4 mg

  18. Milk Proteins: • Caseins • Whey proteins

  19. Milk Proteins: • Caseins are also called phosphoproteins and they are organized in orderly fashion to form micelles. 2/3 of calcium present in milk is associated with casein micelles. Kappa casein play important role in stabilizing casein micelles • Rennin is the enzyme that destroys the protective effect of kappa- casein. Upon action of rennin milk separates into curds and whey. The process of formation curds is called clotting. The whey formed after separation of curd is known as sweet whey. • Kappa casein para-kappa-casein + macropeptide aggregation of casein micelles to form a curd. • Milk clotting can also be caused by acid • Calcium phosphocaseinate curd + calcium.

  20. Cooking of Milk • Cooking affects both the flavor and odor of milk • Flavor changes in milk after prolonged cooking >74C are brought about by Maillard reaction • Changes in odor are believed to be brought about by formation of sulfur containing volatile that are created by denaturation of whey proteins • Caseins are heat resistant: coagulation may take place after 14 hrs of heating at 100 C or after 1h at 130C • Heated milk forms a precipitate on the bottom and sides of cooking pan. • Milk heated in uncovered pan forms a skin made of coagulated proteins, fat and minerals. Formation of skin can be prevented by covering the pan or stirring milk during heating.

  21. Milk Processing

  22. Homogenization • A mechanical process that breaks up the fat globules in milk into smaller globules surrounded by lipoprotein membrane that do not clump together and are permanently dispersed in a very fine emulsion • Carried out by pumping milk under high pressure through fine holes

  23. Homogenization

  24. Whipped Milk Products • Whipped Cream Fat Content Temperature Age Sugar Whipping Time • Whipped Evaporated Milk • Nonfat Dry Milk

  25. Whipped Milk Foam Structure • During Whipping Protein is Mechanically Stretched into Thin Layers that Trap • Air Bubbles • Fat Particles • Liquid

  26. Volumes of whipped milk products

  27. Processing • Evaporation - about 60% water is removed. Milk is pasteurized at 95C for 10-20 min to stabilize caseins. Milk is evaporated under vacuum, some stabilizers may be added before canning. • Drying - milk is first evaporated under vacuum and then spray dried. Instant milk is produced by moistening the surface of NFDM particles, allowing them to agglomerate, and the redrying • Freezing - milk can be frozen for a short time. Prolonged frozen storage destabilizes casein micelles - curdling.

  28. Refrigerated All Fluid Milk except Unopened Aseptic Packs of UHT Milk & Certain Canned Milk Products Storage Guidelines Milk≤ 3 weeks Yogurt up to 3-6 wks Buttermilk3-4 days or up to 3-4 weeks Sour Cream Unopened up to 1 month Best used w/i a few days upon opening Milk storage

  29. Milk storage • Nonfat Dry Milk -Dry Tightly Closed Containers ~ 1 Year • Unopened Evaporated & Sweetened Condensed Milk Up To 1 Year in Dry Ventilated Areas Double That If Refrigerated • Ultrapasteurized Milk Unopened At Room Temperature Up to 3 Months • Stored At or Slightly Below Room Temperature 72°F/22°C • Once Opened All Must Be Refrigerated

  30. CHEESE Chapter 10

  31. Cheese is a product made from curd obtained from the whole, partly fat-free/non-fat, or fat-free/non-fat milk of cows or from milk of other animals, with or without added cream, by coagulating with rennin, lactic acid or other suitable enzyme or acid and with or without further treatment of the separated curd by heat or pressure, or by means of ripening ferments, special molds, or seasoning.

  32. Canada has standards for some 50 cheeses in the Food and Drug Regulations, including the popular Cheddar. Cheddar: is the product made by coagulating milk, milk products or a combination thereof with the aid of bacteria to form a curd and subjecting the curd to the cheddar process or a process that produces a cheese having the same physical, chemical and organoleptic properties as those of cheese produced by the cheddar process. It must have a casein content that is derived from milk or ultra-filtered milk, partly skimmed milk, ultra-filtered partly skimmed milk, skim milk, ultra-filtered skim milk or cream, rather than from other milk products, that is at least 83 per cent of the total protein content of the cheese. Cheddar cheese unless it is made exclusively with milk, ultra-filtered milk, partly skimmed milk, ultra-filtered partly skimmed milk, skim milk, ultrafiltered skim milk or cream or a combination of those things, and unless it hasbeen aged for at least nine months.

  33. Cheese are classified based on • Microbial Characteristics • Appearance • Mode of Packaging • Place of Origin • Processing Method • Milk Source • Moisture Content

  34. Cheese classification Moisture Content • Fresh Country Cheese >80% Cottage Cream Ricotta • Soft 50-75% Brie Camembert Hispanic Cheeses • Semi-Hard 40-50% Roquefort Blue Muenster Brick Gouda • Hard 30-40% Cheddar Swiss • Very Hard 30% Parmesan Romano

  35. CHEESE

  36. Cheese production Milk Selection Greatest Influence • U.S. Pasteurized Cow’s Milk • Europe Middle East Sheep or Goat • Iran Afghanistan Camel • Lapland Reindeer • Mongolia Horse • Philippines India Italy Water Buffalo • China Tibet Yak Zebu

  37. Cheese production • Coagulation: enzyme or acid • Curd treatment involves: • Cutting: to increase surface area- to remove more whey • Heating: to evaporate water, to destroy bacteria • Salting: to dehydrate curd, to control bacterial growth, flavor, texture • Knitting: the use of heat to combine curd • Pressing to create more solid mass before ripening • Curing or ripening: exposure of cheese to controlled temperature and humidity conditions to promote chemical and physical changes in cheese.

  38. Cheese production Coagulation • Casein Protein • Method Determines Characteristics • Two Methods Enzymes Acid

  39. Cheese production - texture Acid Curd Texture • Soft Spongy • Influenced By pH • Solid & Compact As Acidity Increases

  40. Cheese Production Curd Remove More Whey • Cutting • Heating • Salting • Knitting optional • Pressing optional

  41. Cheese Production • Curing Temperature & Humidity Control during Aging • Ripening Chemical & Physical Changes during Curing

  42. CHEESES

  43. Processed Cheese

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