Determination of whey proteins in different types of milk

Abstract

Protein analysis is very important both in terms of milk protein allergy, and of milk and dairy product adulteration (β-lactoglobulin may be an important marker in the detection of milk adulteration). The aim of this study was to detect major whey proteins α-lactalbumin and β-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 α-lactalbumin was higher in goat’s milk (1.27 ± 0.05 g·l -1 , P < 0.001) and cow’s milk (1.16 ± 0.02 g·l -1 , P = 0.0037) compared to sheep’s milk (0.95 ± 0.06 g·l -1 ); however, concentration of α-lactalbumin in goat’s milk and cow’s milk did not differ significantly ( P < 0.05). Goat’s milk contained less β-lactoglobulin (3.07 ± 0.08 g·l -1 ) compared to cow’s milk (4.10 ± 0.04 g·l -1 , P < 0.001) or sheep’s milk (5.97 ± 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 β-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.