Milk PDF - 2003

Understanding Food Amy Brown Chapter 11: Milk Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Composition of Milk The basic composition of milk regardless of the source remains the same: – Water 87.3% – Carbohydrate 4.8% – Protein 3.4% – Fat 3.7% – Minerals 0.8% Slide Deve...

Understanding Food Amy Brown Chapter 11: Milk Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Composition of Milk The basic composition of milk regardless of the source remains the same: – Water 87.3% – Carbohydrate 4.8% – Protein 3.4% – Fat 3.7% – Minerals 0.8% Slide Development: Lonnie M. Lowery, Ph.D. Among domesticated cattle, the breed, stage of lactation, type of feed ingested, and season of the year all tend to slightly influence milk’s content. Copyright 2003 Thomson Learning Composition of Milk Slide Development: Lonnie M. Lowery, Ph.D. Casein: The primary protein (80%) found in milk; it can be precipitated (solidified out of solution) with acid or certain enzymes. Whey: The liquid portion of milk, consisting primarily of 93% water, lactose, and whey proteins (primarily lactalbumin and lactoglobulin). – It is the watery component removed from the curd in cheese manufacture. Copyright 2003 Thomson Learning Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Purchasing Milk Milk is graded according to its bacterial count. The highest grade, Grade A, has the lowest count. The law requires that all Grade A milk and milk products crossing state lines must be pasteurized. Grade B is also available. In addition, different grades exist for fat-free (nonfat) dry milk: U.S. Extra and U.S. Standard. Grading is voluntary and is paid for by the dairy industry. The USDA is responsible for grading. Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Purchasing Milk Ultrapasteurization: A process in which a milk product is heated at or above 280°F (138°C) for at least two seconds. Ultrahigh-temperature (UHT) Milk: Milk that has been pasteurized using very high temperatures, is aseptically sealed, and is capable of being stored unrefrigerated for up to three months. Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Purchasing Milk Slide Development: Lonnie M. Lowery, Ph.D. Homogenization: A mechanical process that breaks up the fat globules in milk into much smaller globules that do not clump together and are permanently dispersed in a very fine emulsion. Coagulate: To clot or become semisolid. In milk, denatured proteins often separate from the liquid by coagulation. Milk solids-not-fat (MSNF): Federal standard identifying the total solids, primarily proteins and lactose, found in milk, minus the fat. Copyright 2003 Thomson Learning Types of Milk About half the milk produced in the United States is sold as fluid milk and cream. Much of the rest comes to market as butter, cheese, and ice cream. Slide Development: Lonnie M. Lowery, Ph.D. The available market forms of milk include fluid milk: – Whole – Reduced fat (2%) – Low fat (1%) – Fat-free (nonfat) – UHT – Chocolate – Canned And many others Copyright 2003 Thomson Learning Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Types of Milk Imitation milk: A product defined by the FDA as having the appearance, taste, and function of its original counterpart but as being nutritionally inferior. Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Types of Milk Cultured or fermented milk products have been used for centuries. Some cultured milk products commonly consumed in North America are: – Buttermilk – Yogurt – Acidophilus milk – Kefir – Sour cream Agglomerate: A process in which small particles gather into a mass or ball. In the case of milk, the protein particles regroup into larger, more porous particles. Curd: The coagulated or thickened part of milk. Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Types of Milk To be called yogurt, the milk product must contain at least 8.25 % MSNF and 0.5% acid. Fat content requirements for yogurt: – Whole 3.25% – Reduced-fat (2%) 0.5 to 3.0% – Fat-free (nonfat) less than 0.5% Slide Development: Lonnie M. Lowery, Ph.D. Probiotics: Live microbial food ingredients (i.e., bacteria) that have a beneficial effect on human health. Prebiotics: Nondigestible food ingredients (generally fibers such as fructooligosaccharides (FOS) and inulin) that support the growth of probiotics. Copyright 2003 Thomson Learning Milk Products in Food Preparation Flavor Changes The bland, slightly sweet flavor of milk comes from its lactose, salts, sulfur compounds, and short-chain fatty acids. The percentage of fat determines the mouthfeel and body of a particular milk. Exposure to heat or sunlight, oxidation, the use of copper equipment or utensils, and the feed ingested by the source animal are just some of the other factors that can influence the flavor of milk. Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Milk Products in Food Preparation Some milk proteins coagulate or precipitate to form a solid clot, or curd, under certain conditions. These conditions include: – Application of heat – Addition of: Acid Enzymes Polyphenolic compounds Salts Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Milk Products in Food Preparation Adding acid to milk causes the casein in the milk to coagulate. Milk also coagulates and forms curds when it is combined with certain enzymes originating from animal, plant, or microbial sources. – Rennin: An enzyme obtained from the inner lining of a calf ’s stomach and sold commercially as rennet. Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Milk Products in Food Preparation Whipped Milk Products During whipping, the protein in these milk products is mechanically stretched into thin layers that trap air bubbles, fat particles, and liquid. Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Milk Products in Food Preparation Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning Storage of Milk Products Refrigerated All fluid milk except unopened, aseptic packs of ultrahightemperature pasteurized milk and certain canned milk products should be stored in the refrigerator. Slide Development: Lonnie M. Lowery, Ph.D. The following guidelines should be followed when storing milk products in the refrigerator: – Milk. No more than three weeks. – Yogurt. Best consumed within the first ten days, but can last up to three to six weeks. – Buttermilk. Best when used within three to four days after purchase, but it can last up to three or four weeks. – Sour cream. Unopened, up to one month, but is best when used within a few days. Copyright 2003 Thomson Learning Storage of Milk Products Dry Storage Nonfat dry milk stored away from moisture and in tightly closed containers will keep for about one year. Unopened cans of evaporated and sweetened condensed milks will keep up to a year in dry, ventilated areas, double that if refrigerated. Ultrapasteurized milk can be stored unopened at room temperature for up to three months. They should all be stored at or slightly below room temperature (72°F/22°C). Once opened, all these milks must be refrigerated. Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2003 Thomson Learning