Free Thiol Content Analysis in Heated Milk

Abstract

Chemical changes, denaturation of whey protein, lysine content decrease and hydroxymethylfurfural (HMF) formation, occur during pasteurization and ultra high temperature (UHT) processes. These changes act as heat indices of milk and milk products. In the detection of an adulteration of reconstituted milk in milk samples, hydroxymethylfurfural is the index used routinely as a reference. In this study, free thiol contents of raw milk, reconstituted milk and mixed milk samples after pasteurization and UHT processes, were determined. The results revealed that free thiol content can differentiate between raw milk and reconstituted milk. The significant correlation between the percentage of reconstituted milk in mixed samples and free thiol is r² = 0.98. Thus free thiol content could be a new indicator for detection of reconstituted milk in raw milk.