The influence of storage conditions on the content and composition of proteolipids in UHT commercial milk

摘要

The objective of the study was to investigate the effect of storage conditions on the content and composition of proteolipids in samples of UHT milk from winter and summer production heated by direct and indirect method. As a result of storage at 4 or22°C the content of proteolipids decreased in all samples. The protein content of proteolipids in samples produced by both methods was comparable and increased at both temperatures during storage. The lipid content in proteolipids present in those products decreased during storage; the temperature did not have a significant influence on the changes. Electrophoretic studies on the composition of protein fractions of proteolipids from UHT milk showed alpha_(s1)-casein, alpha_(s2)-casein, ss- casein, K-casein as well as ss-lactoglobulin and alpha-lactalbumin It was also found that the fatty acids composition in proteolipid fat was comparable. The storage of UHT milk did not affect significantly the changes in the fatty acids compositions of the proteolipid fats.