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MILK
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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
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Terms To Know 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
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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
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Fluid Milk
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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
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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
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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
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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
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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
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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
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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
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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 degrees for 2 to 6 seconds Milk is aseptically packaged and does not require refrigeration until it is opened
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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
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Butterfat: Cream Comes from the separator with a fat content of 35-45%
Used for further processing in the dairy industry—ice cream, butter
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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
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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
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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
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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
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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
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Milk Products and By-Products
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Milk Products and By-Products
Include Butter Concentrated and dried milk Cheese Whey products Yogurt Fermented products Ice Cream
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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
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Butter Make-Up Normal Salted Butter Fat 80-82% Water 15.6-17.6%
Proteins, Calcium, Phosphorous 1.2% Also contains fat soluble vitamins A, D, E
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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
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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 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
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Butter Churns From the Past
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Today’s Butter Churn
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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
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Concentrated and Dried Dairy Products
Concentrated Products Evaporated skim or whole milk Sweetened condensed milk Condensed buttermilk Condensed whey Dried Products Milk Powder Whey Powder Whey Protein concentrates
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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
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Cheese Making Steps Treat milk Additives Inoculation and milk ripening
Coagulation Enzyme Acid Heat-acid Curd Treatment Cheese ripening
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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)
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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
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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
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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 % 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
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Basic Steps In Manufacturing Ice Cream
Blending of the mix ingredients Pasteurization Homogenization Aging the mix Freezing Packaging Hardening
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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
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Milk Substitutes Margarine Frozen desserts Coffee whiteners
Whipped toppings Soy milk All are made by combining nondairy fats with certain classes of milk components
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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?
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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
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Lab Making Butter
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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
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