MILK

1. MILK

2. Objectives • Define the term “milk” • Describe quality control during the production of milk and milk products • Explain pasteurization and homogenization • Identify three methods of pasteurization • Describe the “solids” composition of milk • Discuss the separation of butterfat and its use • List four beverage milk products • Describe butter • Name 5 concentrated or dried dairy products • List the steps in the cheese making process • Identify 3 bacteria used to produce dairy products • Name 5 fermented dairy products • List the steps in making and ice cream and make ice cream • Describe the USDA quality grade shields

3. Buttermilk Churning Coalesce Curd HTST Lipolysis LTLT Rennet Ripening Ropey Solids-not-fat Standard plate count (SPC) standardized Ropey Solids-not-fat Standard plate count (SPC) standardized Thermization UHT Ultrapasteurization Vaccum evaporation Whey Terms To Know

4. Introduction • Milk: the first food for young mammals • Provides high quality protein, vitamins and minerals and is a source of energy • Worldwide many mammilian species are used to produce milk and milk products • Goats, sheep, horses, yaks • However, our focus will be on milk from dairy cows

5. Fluid Milk

6. Fluid Milk • Collodial dispersion of the protein caesin and the whey proteins. It is an emulsion with fat globules suspeneded in the water phase • Composed mainly of water • 87-89% • Milk solids make up the other 12-13% • Solids include the carbs, lactose, fat, protein and minerals • Solids-not-fat • Excludes the fat and includes the caesin, whey, lactose, proteins, minerals

7. Production Practices • Fewer cows are producing more milk • Daries are becoming larger • In major production areas daries are 1,000 cows or more • Milk fresh from the cow is virtually sterile • Post handling must maintain the milks nutritional value and prevent deterioration caused by physical and biological changes • Equipement must be maintained to government and industry standards

8. Production Practices • Cows are milked twice a day • Some farms milk 3-4 times/day • Milk is immediately cooled from the body temperture of the cow to below 41 degrees F • It is then stored at the farm under refrigeration until it is picked up by tanker trucks at least every other day • A sample of the milk is collected at this time for later lab analysis

9. Quality Control • On the farm • Inspectors monitor herd health, farm water supply, sanitation, milk temperture, holding times, bacteria counts • Violations of health standards result in heavy penalties up to and including suspension from business • Inspections occur both at the farm and processing plants on a regular on-going basis • Inspectors have full authority to suspend plant operations in order to conduct detailed examinations of all equipment, facilities and products • The dairy industry works hard to ensure that they comply with or exceed all regulations

10. Quality Control • Finished dairy products • Tested regularly by state inspectors to ensure compliance with • Standards of Identity • Refers to criteria such as mouisture, butterfat, protein content • Purity • Refers to pathogens and residues criteria • The Food and Drug Administration (FDA) sets the standards of identity for beverage milk products

11. Processing • When milk arrives at the plant it is checked to make sure that it meets the standards for temperture, total acidity, flavor, odor, tanker cleanliness and absence of antibiotics • Butterfat and solids-not-fat content is analyzed • These amounts will vary with the feed, breed of cow and time of year • These are also used along with the volume to determine what the producer will be paid • Once the milk passes these receiving test it is pumped into large refrigerated silos

12. Pasteurizing • Heating the raw milk to kill all pathogenic microoranisms that may be present • Not sterilization • After pasteurization some harmless bacteria may still be present • these are the bacteria that cause milk to go sour • Refrigeration is the best way to slow the growth of these organisims

13. Pasteurizing • Low Temperture Longer Time (LTLT) • Heats milk to at least 145 degrees F for at least 30 minutes • Can cause a “cooked” flavor • Not used by some milk plants for fluid milk products • High Temperture/Short Time (HTST) • Heats milk to at least 161 degrees F for at least 15 seconds • Milk is immediately cooled to below 40 degrees F and packaged in plastic jugs or plastic coated cartons • Ultrapasteurization • Heating milk to 280 degrees F or higher for 2 seconds followed by rapid cooling to 45 degrees or less • Ultrahigh Temperture Processing • Sterilizes the milk • Heats it to 280-302 degrees for 2 to 6 seconds • Milk is aseptically packaged and does not require refrigeration until it is opened

14. Butterfat • Several different types of product • Whole milk, 2%, 1%, nonfat, Half & Half • Seperated using separator that separates the cream and skim portions of the milk • For example: During the separation of whole milk two streams are produced: the fat-depleted stream, which the above mentioned beverage milks are made of; skim milk for evaporation and/or drying and the fat-rich stream, the cream

15. Butterfat: Cream • Comes from the separator with a fat content of 35-45% • Used for further processing in the dairy industry—ice cream, butter

16. Homogenization • Prevents the cream from rising to the top • A “homogenizer” forces milk under high pressuure through a valve that breaks up butterfat globules to such a small size that they will not coalesce (stick together) • Does not affect the nutrion or quality

17. Beverage Milk • Most raw milk fat content is 4% or higher • Most beverage milk is 3.4% • Lower fat contents- 2%, 1%, Skim • These products are produced by partial or complete skimming and then adding cream back to achieve the final desired fat content

18. Nutritional Qualities • Vitamins may be added • A & D most often due to their loss • A during fat separation and heating • D because it is not present in milk • Supplemeted in the form of a water-soluble emulsion • Many states have milk standards that require the addition of milk solids • These represent the natural mineral, protein, and sugar portion of nonfat dry milk

19. Quality Control • Numerous test on raw and paterurized product • Microbial organisims are tested for using the standard plate count (SPC) and ropey milk test • Equipment used to analyze butterfat and solids-not-fat is calibrated on a regular basis to ensure consistency • All products have a sell-by date • Samples of the products packaged each day are saved to confirm they maintain their freshness 7 days after the sell-by date

20. Packaging • Once milk is separated, standardized, homogenized and pasteurized it is held below 40 degrees F • Then it is packaged into gallon, ½ gallon, quart, pint and half pint containers • Packaging machines are maintained under strict standards • All equipment is washed daily • Automatic clean-in-place systems guarantee consistent sanitation with minimum manual handling to reduce the risk of contamination • Once packaged the products are conveyored to cold storage where they are stored for a short time before being shipped to supermarkets where they are kept in cold storage or refrigerated display cases

21. Milk Products and By-Products

22. Milk Products and By-Products • Include • Butter • Concentrated and dried milk • Cheese • Whey products • Yogurt • Fermented products • Ice Cream

23. Butter • Made by churning pasteurized cream • Churning breaks up the fat globule membrane • This breaks the emulsion, fat coalesces and the water (buttermilk) escapes • Federal law requires that it contain at least 80% milkfat, nutritionally butter is a fat. • Salt and coloring may be added • Today commercial butter making is a product of knowledge and experience gained over the years

24. Butter Make-Up • Normal Salted Butter • Fat 80-82% • Water 15.6-17.6% • Salt 1.2% • Proteins, Calcium, Phosphorous 1.2% • Also contains fat soluble vitamins A, D, E

25. Butter • Should have uniform color • Be dense • Taste clean • Water should be dispersed in fine droplets so that the butter looks dry • Consistency should be smooth so that it is easy to spread and melts readily on the tongue

26. Making Butter • From storage tanks the cream goes to pasteurization • This destroys enzymes and microorganisms that would impair the keeping quality of the butter • Next, ripening • Here the cream is subject to a program of heat treatments designed to give the fat the necessary crystaline structure so it solidifies on cooling • Takes 12-15 hours • Churning • Cream is violently agitated • This breaks down the fat globules, causing the fat to coagulate into butter grains, leaving the liquid part (buttermilk) • Butter is salted and worked to ensure even distribution • Packaged • Sent to cold storage

27. Butter Churns From the Past

28. Today’s Butter Churn

29. Concentrated and Dried Dairy Products • Concentrated products have partial water removal • Dried products have water removed to less than 4% • Benefits of both products are • Increased shelf life • Convenience • Product flexibility • Decreased transportation costs • Storage

30. Concentrated Products Evaporated skim or whole milk Sweetened condensed milk Condensed buttermilk Condensed whey Dried Products Milk Powder Whey Powder Whey Protein concentrates Concentrated and Dried Dairy Products

31. Cheese • Traditionally cheese was made as a way of preserving the nutrients of milk • Cheese- the fresh or ripened product obtained after coagulation and whey seperation of milk, cream, or partly skimmed milk, buttermilk or a mixture of these • THOUSANDS of varieties

32. Cheese Making Steps • Treat milk • Additives • Inoculation and milk ripening • Coagulation • Enzyme • Acid • Heat-acid • Curd Treatment • Cheese ripening

33. Yogurt • Semisolid fermented milk product • Originated in Bulgaria • Milk from a variety of animals is used in yogurt production but most of the industrialized nations use cow’s milk • Starter culture used in most yogurt production is a blend of Streptococcus salivarius thermophilus (ST) and Lactobacillus delbruekii bulgaricus (LB)

34. Making Yogurt • Milk is clarified and separated into cream and skim milk • Standardized to achieve the desired fat content • Various ingredients are blended together in a mix tank equipped with a power funnel and an agitation system • Mixture is then pasteurized • Once the homgenized mix has cooled to an optimum growth temperature, the yogurt starter culture is added

35. Fermented Milk Beverages • Cultured Buttermilk • Once a by-product of butter production, now produced from whole or skim milk • Acidophilus Milk • Traditional milk fermented with LA which is thought to have therapeutic benefits in the gastrointestinal tract • Sour Cream • Others

36. Ice Cream (start) • Greater than 10% milk fat by legal definition • As high as 16% fat in some premium ice cream • 9-12% milk solids-not-fat • Also contains 12-16% sweeteners-usually a combination of sucrose and glucose-based corn syrup sweeteners • 0.2-0.5% stabilizers and emulsifiers • 55-64% water from the milk or other ingredients • When frozen about half the volume of ice cream is air • All ice cream is made from a basic white mix

37. Basic Steps In Manufacturing Ice Cream • Blending of the mix ingredients • Pasteurization • Homogenization • Aging the mix • Freezing • Packaging • Hardening

38. Quality Products • Established by USDA • Grades are used to describe different grades of quality in butter, cheese (Cheddar, Colby, Monterey, Swiss) • FDA established the Grade A designation for fluid milk products, yogurt and cottage cheese • Grade standards are used to • Identify levels of quality • Provide a basis for establishing prices at wholesale • Supply Conumers with a choice of quality levels

39. Milk Substitutes • Margarine • Frozen desserts • Coffee whiteners • Whipped toppings • Soy milk • All are made by combining nondairy fats with certain classes of milk components

40. Reduced Fat Products • Brought on to the market in the effort to reduce calories, saturated fat, cholesterol • When fat is replaced the replacement must perform the same functions as the fat. • It must give the product the same texture or “mouth feel” • Why? • What would consumer repsonse be if it didn’t?

41. Summary • Milk provides high quality protein, energy, vitamins, minerals • Dairy industry provides a variety of milk products • USDA and FDA maintain quality standards • Milk is pasteurized to protect consumers against pathogens • Milk is homogenized to keep milk fat in suspension • Butterfat is separated from the milk to be added back in in the desired amounts • Concentrated and dried products increase shelf life and convenience and decrease transportation costs • USDA established grade standards for butter, cheese and instant nonfat dry milk • FDA established grade designations for fluid milk, yogurt, cottage cheese • Only officially graded products carry a grade shield • In an effort to meet consumer demands the food industry has developed milk and milk substitutes and reduced fat products

42. Lab • Making Butter

43. STUDENT ACTIVITY • Develop a presentation comparing BUTTER to MARGARINE • Compare their make-up (ie-butter is made from milk fat and margarine is made from vegetable oil) • Compare their healthfullness • Find pictures • Make a poster