Seasonal Changes in the β-Lactoglobulin, α-Lactalbumin, Glycomacropeptide, and Casein Content of Whey Protein Concentrate

Seasonal changes in the p-lactoglobulin, a-lactalbumin, casein, and glycomacropeptide content of dried whey protein concentrate, manufactured in southeastern Australia, have been measured over consecutive milking seasons by both HPLC and by PAGE under denaturing conditions.Seasonal changes generally in- cluded a reduction in the a-lactalbumin content of whey protein concentrate manufactured during the final three months of lactation, concomitant with a rise in the level of P-lactoglobulin.These changes contrasted with an increase in the casein content of whey protein concentrate prepared during the first 4 mo of lactation.Seasonal variation in the relative proportions of the major protein constituents of whey protein concentrate has important implications for the dairy industry, particularly in the preparation of "tailor-made" whey protein concentrates with specified applications, and in specialized processes such as whey protein fractionation.