Influence of β-lactoglobulin and κ-casein genotype on whey protein denaturation in heated bovine milk and rennet whey

Whey proteins provide nutritional and functional properties in many dairy products, and their denaturation induced by heat has drawn attention in dairy research and industry. Denatured whey proteins have functional properties that are beneficial for certain applications, such as yogurt, while uncontrolled denatured protein aggregation can impair certain processes, such as rennet coagulation. The possible effect of genetic polymorphism of β-lg and κ-CN on heat-induced denaturation of whey proteins in milk and in rennet whey was investigated in this study. No effect of κ-CN genotype on the denaturation of β-lg and α-lac was detected, while the A variant of β-lg was more heat-stable than the B variant. More denatured β-lg B was shown to interact with casein micelles to form insoluble aggregates compared to the A variant. These results may provide guidance for selection of specific milk genotypes for applications where whey protein denaturation needs to be minimised or else preferred, such as foaming and emulsification.