Determination of whey proteins in different types of milk.

摘要

Protein analysis is very important both in terms of milk protein allergy, and of milk and dairy product adulteration ( beta -lactoglobulin may be an important marker in the detection of milk adulteration). The aim of this study was to detect major whey proteins alpha -lactalbumin and beta -lactoglobulin and their genetic variants by reversed-phase high-performance liquid chromatography. Milk samples from cows (n=40), goats (n=40) and sheep (n=40) were collected at two farms and milk bars in the Czech Republic from April to June 2010. The concentration of alpha -lactalbumin was higher in goat's milk (1.27+or-0.05 g.l-1, P<0.001) and cow's milk (1.16+or-0.02 g.l-1, P=0.0037) compared to sheep's milk (0.95+or-0.06 g.l-1); however, concentration of alpha -lactalbumin in goat's milk and cow's milk did not differ significantly (P<0.05). Goat's milk contained less beta -lactoglobulin (3.07+or-0.08 g.l-1) compared to cow's milk (4.10+or-0.04 g.l-1, P<0.001) or sheep's milk (5.97+or-0.24 g.l-1, P<0.001). A highly significant positive correlation (r=0.8686; P<0.001) was found between fraction A and B of beta -lactoglobulin in sheep's milk, whereas in cow's milk there was a negative correlation (r=-0.3010; P=0.0296). This study summarizes actual information of the whey protein content in different types of milk which may be relevant in assessing their allergenic potential.