The Role of Bacterial Proteinases in Gelation Defect of Uht Milk

Ultra high temperature (UHT) is the common means of heat processing for safety and good keeping quality of milk as a microbiologically stable at room temperatures. Gelation is one of the major defects in UHT milk and milk products as it limits the shelf life of the product. It may frequently exhibit certain changes in the flavor and texture during Storage. Many studies have demonstrated that endogenous and bacterial proteinases play an important role in gelation of UHT milk. These enzymes are generally produced by psychrotrophic organisms that grow in milk during refrigerated storage like Pseudomonas and spore forming bacteria like Bacillus that survive heat treatment. To gain more information about the gelation phenomena in UHT milk the present study investigated the role of B. cereus and bacterial proteinases at different temperatures on the gelation of UHT milk. Several parameters that include Bacillus cells count, pH, and proteolysis assessment were monitored during storage.