Effect of Homogenization Pressure on the Milk Fat Globule Membrane Proteins

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Abstract
The effect of high pressure homogenization on the milk fat globule membrane proteins was investigated. Milk with 1.5 or 3.0% milk fat was heated in vats at low or high temperature (65°C for 30 min or 85°C for 20 min), homogenized, cooled, and centrifuged to separate the cream and serum phases. The amount of protein load per surface area increased as homogeni- zation pressure increased but decreased with heat treatment. The composition of the proteins forming the milk fat globule membrane in homogenized milk was not affected by homogenization pressure or fat concentration, but significant differences in the com- position of the milk fat globule membrane were caused by the heat treatment that was applied before homogenization. The milk fat globule membrane pro- teins in homogenized milk were composed of native membrane proteins, caseins, a-lactalbumin, and b- lactoglobulin. Caseins represented about 70% of the proteins in the milk fat globule membrane. In milk heated at 85°C for 20 min, the ratios of adsorbed a- lactalbumin and b-lactoglobulin relative to adsorbed caseins were higher than in milk heated to 65°C.