Electrophoretic Patterns of European Cheeses: Comparison and Quantitation

Abstract

The extent of cheese ripening and the type of proteolysis were measured on many assorted cheese varieties by concentrations of soluble tyrosine and soluble tryptophan, and by quantitative gel electrophoresis. In most varieties, .alpha.S-casein appeared degraded more extensively than .beta.-casein; the relative proportion of products with high electrophoretic mobility from .alpha.S-casein breakdown was less than the slow mobility degradation products from .beta.-casein, probably from the higher resistance of the latter to further hydrolysis and to differences in their dye-binding capacities. Soluble tryptophan and tyrosine concentrations in the cheeses were related directly to hydrolysis of .beta.-casein and to amounts of some of their degradation products (.gamma.2- and .gamma.3-casein) but were not related to the proteolysis of .alpha.S-casein nor to the amounts of their insoluble degradation products nor .gamma.1-casein. The relationships for soluble tyrosine are explained by the primary structures of the caseins and their first soluble and insoluble degradation products. The amounts of residual .beta.-casein were related directly to the moisture content of the cheeses.