Dried milk products

Standards and definitions for whole milk powder, partiy skimmed milk powder, and skimmed milk powder have been set by WHO. This standard apphes exclusively to dried milk products as defined, having a fat content of not mote than 40 mol %. 

Dmm-dried products, mostly nonfat, make up only 5—10% of dried milk products. Because of the high temperature and longer contact time, considerable proteia denaturation occurs. Dmm-dried products ate identified as high heat dry milk and as such have a lower solubHity iadex, lower proteia nitrogen content, and a darker color. 

Lipid hydroperoxides are either formed in an autocatalytic process initiated by hydroxyl radicals or they are formed photochemically. Lipid hydroperoxides, known as the primary lipid oxidation products, are tasteless and odourless, but may be cleaved into the so-called secondary lipid oxidation products by heat or by metal ion catalysis. This transformation of hydroperoxides to secondary lipid oxidation products can thus be seen during chill storage of pork (Nielsen et al, 1997). The secondary lipid oxidation products, like hexanal from linoleic acid, are volatile and provide precooked meats, dried milk products and used frying oil with characteristic off-flavours (Shahidi and Pegg, 1994). They may further react with proteins forming fluorescent protein derivatives derived from initially formed Schiff bases (Tappel, 1956). 

Foodstuffs subject to drying by combustion gases (containing oxides of nitrogen) such as malt for production of beer and whiskey, low-fat dried milk products and spices. 

Because milk is perishable and its production was, traditionally, seasonal, milk surplus to immediate requirements was converted to more stable products, traditional examples being butter or ghee, fermented milk and cheese smaller amounts of dried milk products were produced traditionally by sun-drying. These traditional products are still very important and many new variants thereof have been introduced. In addition, several new products have been developed during the past 130 years, e.g. 

Dried milk and whey. Lactose is the major component of dried milk products whole-milk powder, skim-milk powder and whey powder contain c. 30, 50 and 70% lactose, respectively. Protein, fat and air are dispersed in a continuous phase of amorphous solid lactose. Consequently, the behaviour of lactose has a major impact on the properties of dried milk products. 

Typical analyses of dried milk products sire given in Table 2.4. 

Most dry buttermilk is prepared from sweet cream buttermilk, and is produced in a manner similar to that of nonfat dry milk. Dry buttermilk has a higher phospholipid content than other dry milk products and therefore is a natural emulsifier for use in the dairy and baking industries and for dry mixes and other foods. A dry, high-acid buttermilk can be produced from milk fermented by L. bulgaricus. It is difficult to dry, however, and has found only limited use in the baking industry. There are no United States and FAO standards for this product, although typically the moisture content is less than 5%. 

Procedures based on rotation have been used for quantitative measurement of the amounts of a- and /3-lactose in fluid and dry milk products and in ice cream (Roetman (1981). 

Milk or skim milk is standardized to meet milk fat and total milk solids compositional requirements in the final dry milk product e.g., NFDM must contain <1.5% milk fat DWM must contain >26% and < 40% milk fat, and both must contain <5% moisture on an MSNF basis (CFR, 1982). Dry milk products must also meet U.S. Department of Agriculture and American Dry Milk Institute standards for titratable acidity, scorched particle content, solubility, and bacteria content. Product users may also have specialized requirements for color, flavor, and dispersibility. 

Dried milk products include dried whole milk, dried skim milk and dried whey. The products derived from whole milk and skim milk are very palatable and are highly digestible protein supplements with an excellent balance... 

Each step in the processing and packaging of dry milk products can influence the properties of the finished product. The total heat treatment (i.e., time x temperature) for each step during the manufacture of milk powder is important in determining its properties. The method of heating and the total heat exposure influence protein denaturation, oxidation of the fat and the subsequent shelf-life of the powder. 

Buma, T.J., Henstra, S. 1971. Particle structure of spray-dried milk products as observed by a scanning electron microscope. Neth. Milk Dairy J. 25, 278-281. 

Ultrafiltration processing for whey proteins concentration and fractionation, for recovery of lactose from milk and whey, for total milk protein concentration for the production of milk protein concentrate (MFC) or nulk protein isolate (MPl), for milk standardization for continuous mechanized manufacture of cheese and other fermented products, and for production of high-solids milk base for dried milk production. 

Dehydration. Few texts are devoted solely to this method of food preservation. The U. S. Department of Agriculture has issued an excellent booklet, Vegetable and Fruit Dehydration—A Manual for Plant Operators. There is the text by Von Loesecke on dehydration. Additional information is available in some of the texts mentioiied previously, particularly, Chemistry and Technology of Food and Food Products, and in sections of texts covering special fields, such as Tressler s Marine Products of Commerce and Hunziker s Condensed Milk and Milk Powder which consider dried fish and dried milk products, respectively. 

Water Determination in Dried Milk Products Is the International Standard Method Reasonable ... 

Five dried milk products with various compositions, all provided by Nestle, Vers-chez-les-Blanc, Lausanne, Switzerland, and a-lactose were analyzed ... 

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