Effect of the milk heat treatment on properties of low-fat yogurt manufactured with microbial transglutaminase

Abstract

The effect of milk heat treatment (UHT vs HTST) on physicochemical properties of low-fat set-style yogurt manufactured with microbial transglutaminase was evaluated. It was also evaluated the sensory profile of microbial transglutaminase yogurt and conventional fortified yogurt using skim milk powder. The UHT treatment of milk to make yogurts treated with microbial transglutaminase showed poorer texture results (firmness, consistency, cohesiveness and index of viscosity) than the HTST treatment of milk. Yogurt texture of UHT treatment was also worse than low-fat commercial yogurts, despite of the positive effect of the microbial transglutaminase. The microbial transglutaminase addition avoided the syneresis, regardless of the type of heat treatment. A microbial transglutaminase doses at low levels (0.76 U·g-1 of milk protein) added simultaneously with the starter culture was useful for improving the textural properties and sensory characteristics of low-fat yogurt, avoiding the normal syneresis of low-fat yogurt and without increasing the protein content that happen with the addition of skim milk powder. Yogurts made with microbial transglutaminase with HTST treatment showed significantly lower whey odor than yogurt fortified with skimmed milk powder. The application of microbial transglutaminase is a useful treatment for improving textural properties of low-fat yogurt with the usual pasteurization treatment applied in the dairy industry.