Effects of Whey Proteins on the Proteolysis of Cheddar Cheese Slurries (A Model for the Maturation of Cheeses Made from Ultrafiltered Milk)

Native whey proteins were found to decrease the rate of a s 1-casein proteolysis in Cheddar cheese slurries. This was probably due to chymosin inhibition, since the conversion of % 1 -casein to c~ s i -I was reduced. Denatured whey proteins had little effect on asl-casein degradation. 13-Casein proteolysis was inhibited by both native and denatured whey proteins. The reason for this is uncertain but may involve suppression of both plasmin and chymosin activity. Both native and denatured ~3-1actoglobulin and a-lactalbumin were largely unaffected by the enzymes in slurries. The buildup of pH 4.4 soluble N was inhibited by native whey protein and increased in the presence of denatured whey protein. Despite the difference in proteolysis detected by electrophoresis and soluble N measurements, no differences were found between the flavor of slurries with and without native or denatured whey proteins. Although care must be taken in extrapolating from slurries to Cheddar cheese made from UF milk, whey protein inhibition of proteolytic enzymes may contribute to the atypical maturation patterns that have been reported in such cheese.