Gelation Problem in UHT Milk: Effect of Enzymes

The most prevalent heat treatment method used in the industry to extend shelf life of milk is UHT (Ultra High Temperature) process. However, the gel formation occurred depending on enzymatic and physical effects during storage shortens the shelf life of UHT milk. Heat-stable proteinases produced by psychotropic bacteria, and the native plasmin and plasmin system enzymes in raw milk cause gel formation in UHT milk. These enzymes differently affect casein, which is the most important milk protein, and produce different metabolites in UHT milk. In this review, it is aimed to give information about the mechanism of gelation and enzymes affecting its formation in UHT milk