Dehydrated Milk Products

Skim milk powder and whole milk powder are used either for the reconstitution of milk in countries that for climatic reasons have no dairy farming or as intermediate products for further processing into infant milk products, milk chocolate etc. The quality of these instant products depends on the durability, redissolution capacity (cold and warm), taste, microbiological characteristics, and preservation of essential constituents (proteins, vitamins) during production. 

Using film evaporating systems, the milk is first preconcentrated to 30-55% solids. 

In drum drying, the liquid (30-40% solids) is applied in a thin layer to a heated drying cylinder (100-130 °C) and, after a defined residence time (rotation, 2-3 s), removed with a scraping knife. The liquid film can be applied in various ways. In drum drying, relatively large particles are obtained. The thermal exposure (temperature, time) is considerably higher than in spray drying, which 

In spray drying, the milk concentrate (30-55% solids) is finely dispersed in the spray tower by centrifugal atomization or by nozzle atomization and dried with hot air (150-220 °C) cocurrently or countercurrently. The water content drops to 6-7% in 0.5-1 s. A further decrease to 3-4% is achieved by after drying in a vibration fluid bed with hot air (130-140 °C). 

Other dehydrated dairy products, in addition to whole milk or skim milk powders, are manufactured by similar processes. Products include dehydrated malted milk powder, spray- or roller-dried creams with at least 42% fat content of their solids and a maximum 4% moisture, and butter or cream powders with 70-80% milk fat. Dehydrated buttermilk and lactic acid-soured milk are utilized as children s food. 

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Milk and egg products are highly desired in pet foods since they supply the highest quaHty amino acid profiles with nearly 100% digestibiHty. Most milk protein concentrates are used for human foods, but some are available to pets (see Milk and milk products). An enormous quantity of whole eggs (qv) derived from egg graders, egg breakers, and hatchery operations are handled as dehydrated, Hquid, or frozen ingredients. 

Sucrose Esters. These newer emulsifiers, approved for direct addition in the United States in 1983 (35), ate formed when sucrose is combined with various fatty acids and the resulting emulsion is dehydrated. These additives are odorless and tasteless, and can withstand the retort process. They are used in products when standards of identity do not preclude their use, such as baked goods, baking mixes, dairy product analogues, fto2en dairy desserts and mixes, and whipped milk products (39). High price has limited use in the United States, but these compounds ate used extensively in Japan as emulsifiers in baked goods (40). 

Annex II lists foodstuffs for which only certain of the annex I additives may be used. Such foodstuffs include cocoa products and chocolate products, fruit juices and nectars, jam, jellies and marmalades and partially dehydrated and dehydrated milk, which are the subjects of EU vertical standards, and a number of other foods including frozen unprocessed fmit and vegetables, quick-cook rice, non-emulsified oils and fats, canned and bottled fruit and vegetables, bread made with basic ingredients only, fresh pasta and beer. 

Lactose and casein are the two principal reactants in the browning of milk products, but dried whey products containing lactose also undergo browning. Holsinger et al. (1973) studied the variation of total and available lysine in dehydrated products from cheese wheys by different processes. Roller-dried products showed significant losses in ly-... 

This text on milk lipids is the second in a series entitled Developments in Dairy Chemistry, the first being devoted to milk proteins. The series is produced as a co-ordinated treatise on dairy chemistry with the objective of providing an authoritative reference source for lecturers, researchers and advanced students. The biosynthesis, chemical, physical and nutritional properties of milk lipids have been reviewed in eight chapters by world experts. However, space does not permit consideration of the more product-related aspects of milk lipids which play major functional roles in several dairy products, especially cheese, dehydrated milks and butter. 

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. 

Many adults, and some children, are unable to hydrolyze lactose because they do not make the enzyme lactase. This condition, which affects 20% of the population of the United States, is known as lactose intolerance. Undigested lactose remains in the intestinal tract and causes cramping and diarrhea that can eventually lead to dehydration. Some of the lactose is metabolized by intestinal bacteria that release organic acids and CO2 gas into the intestines, causing further discomfort. Lactose intolerance is unpleasant, but its effects can be avoided by a diet that excludes milk and milk products. Alternatively, the enzyme that hydrolyzes lactose is available in tablet form. When ingested with dairy products it breaks down the lactose, preventing symptoms. 

Products and Uses Used in baked goods, bakery mixes, frozen desserts, fruit juices (dehydrated), fruits (dehydrated), milk or cream substitutes for beverage coffee, pancake mixes, pudding mixes, rice (precooked instant), shortening (liquid), vegetable juices (dehydrated), and vegetables (dehydrated). It is an emulsifier (stabilizes and maintains mixes to aid in suspension of oily liquids). 

Dehydrated milk-based foods is the major source of D-lactulose-amino acids in human nutrition. The dairy industry widely uses milk dehydration to manufacture powdered milk as a base for numerous dairy products, such as infant formulas, confectionaries, reconstituted milk etc. During the process of heating, drying and storage, lactose in milk can readily interact with amino compounds that are naturally present, primarily lysine residues in milk proteins. Estimated contents of D-lactulose-amino acids in selected products are compiled in Table 2. Commercial dairy products may contain, therefore, up to 40% of protein lysine in form of lactulose-lysine. Dietary availability of D-lactulose-amino acids is similar to that of the fructosamine derivatives. An ample evidence exists that the Amadori-type lysine glycoconjugates are not available to mammals as a nutrient and that lactulose-lysine is partially absorbed into the bloodstream and excreted unchanged. ... 

Milk of lime is added to neutralize remaining sulfurous acid, and CaS03 and ZnS03 are removed by filtration. Common salt is added to the remaining solution to salt out Na2S204 2H20. The suspension of crystals is heated to to dehydrate the product, water is extracted with alcohol, and the product crystals are vacuum-dried. The crystals are stable only when completely dry. 

Other examples are glycine — formaldehyde, alanine — acetaldehyde, valine — isobutyraldehyde, phenylalanine — phenylacetaldehyde, and methionine — methional (106). Products such as dried skim milk, dried eggs, and dehydrated vegetables and fmits are particularly susceptible to deteriorative flavor changes ascribed to this reaction (Table 10). 

Pasteurized blended cheese =S43 >41 Cheese cream, anhydrous milk fat, dehydrated cream (in quantities such that the fat derived from them is less than 5% (w/w) in finished product) water salt food-grade colours, spices and flavours mould inhibitors (sorbic acid, potassium/sodium sorbate, and/or sodium/calcium propionates), at levels sgO.2% (w/w) finished product... 

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