Sterile milk

Packaging. Aseptic packaging was developed in conjunction with high temperature processing and has contributed to make sterilized milk and milk products a commercial reaUty. 

Dauer-haftigkeit, /, durability, permanence, -haltbarkeit, /. Mech.) fatigue endurance, -hefe, /. permanent yeast, zymin. -leistung, /. continuous output, -magnet, m. permanent magnet, -milch,/, sterilized milk condensed milk dried milk. 

Though unacceptable to humans, the radiated foods seem palatable to bacteria. Thus satisfactory cottage cheese has been made from sterilized milk. 

Figure 2.35 (a) Scheme for manufacture of low-lactose milk using a high level of soluble /)-galactosidase. (b) Scheme for the manufacture of low-lactose milk by addition of a low level of soluble / -galactosidase to UHT-sterilized milk. (Redrawn from Mahoney, 1997.)... 

The products of Maillard browning have a significant negative impact on the flavour of heated milk products, especially in-container sterilized milks and milk powders. 

Ultra-High-Temperature (UHT) Sterile Milk. Rapid increases in the production and sales of sterile, fluid milk in Europe and its entry into new markets around the world merit its consideration in this chapter. Although the gross composition of UHT sterile, aseptically packaged milk is essentially the same as that of its pasteurized counterpart, differences in its properties and minor constituents should be mentioned. 

Burton, H. 1982. Sterilized milk and milk products. In CRC Handbook of Processing and Utilization in Agriculture, Vol. I, Animal Products. I. A. Wolff (Editor). CRC Press, Boca Raton, Fla., pp. 379-387. 

Chiofalo, L. and Iannuzzi, L. 1963. Variations in some properties of sterilized milk during storage. Zootec e Vita 6, 32-55. In DSA 27, 1287, 1965,... 

Higginbottom, C. and Taylor, M. M. 1960. The oxidation-reduction potential of sterilized milk. J. Dairy Res. 27, 245-257. 

Most of the developmental research and production of UHT sterile milk, which does not require refrigerated storage, has been in Europe, where home refrigeration is minimal. Until now, the U.S. dairy industry has been slow to promote this new product, since home refrigeration is universally available and the consumer is not accustomed to its highly heated flavor. 

The sterile milk concentrate is aseptically placed in suitable containers, probably metal cans or modem laminated, foil-lined, plastic containers. Modern aseptic packaging equipment used for manufacturing UHT sterile milk should be satisfactory for packaging the sterile milk concentrate. 

Age thickening is a common defect of UHT sterile milk concentrate, which has received less drastic heat treatment than conventionally sterilized evaporated milk (Harwalker 1982). Age thickening is promoted by high milk solids content, addition of alkali to raise the pH, and addition of citrate, phosphate, and other anions that lower the Ca ion activity. Conversely, addition of Ca ions improves stability of the product against age thickening. 

Harwalker, V. R. 1982. Age gelation of sterilized milks. Ik Developments in Dairy Chemistry, Vol. 1 Proteins. P. F. Fox (Editor). Applied Science Publishers, New York, pp. 229-265. 

Mehta, R. S. and Bassette, R. (1978). Organoleptic, chemical and microbiolgical changes in ultra-high-temperature sterilized milk stored at room temperature. ]. Food Prot. 41, 806-810. 

These nonenzymatic reactions are responsible for numerous changes on food properties and may impair food safety. Although these reactions are of great importance in the production of aroma, taste and color, they are often accompanied by a reduction of the nutritive value of different foods and by the formation of toxic compounds harmful for human health (Ledl and Schleicher, 1990). Results of nonenzymatic browning can be either desirable or undesirable. The brown crust formation on bread is desirable the brown discoloration of evaporated and sterilized milk is undesirable. For products in which the browning reaction is favorable, the resulting color and flavor characteristics are generally experienced as pleasant. In other products, color and flavor may become quite unpleasant. 

Nisin Preparation occurs as a white, free-flowing powder. It is a mixture of closely related polypeptides produced by strains of the Lactococcus lactis subsp. lactis Lancefield Group N in a sterilized milk-culture medium. Nisin in the fermentation broth can be recovered by various methods, such as injecting sterile, compressed air (froth concentration) acidification salting out and spray-drying. 

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