Effect of transglutaminase addition to chemical, physical, and culture survivability of yogurt during storage period

One way to improve the physical and sensory properties of low fat or nonfat yogurt is by adding a small amount of transglutaminase enzyme into yogurt. Transglutaminase is an enzyme that can cause crosslinking in proteins and is particularly suited for improving the functional properties of food proteins. This study was conducted in order to evaluate the effect of transglutaminase (TGase) addition on some properties of yogurt such as fermentation time, pH, total of lactic acid bacteria, syneresis, viscosity, and microstructure. The enzyme was added at different production steps, those are before addition of starter culture and simultaneously with starter culture addition. Another variations are the concentration of the enzyme (0.5; 1.0; and 2 grams enzyme/gram milk protein) and the storage period (1, 8, and 15 days of storage period). It was shown that there were no significant effect of transglutaminase addition to fermentation time. Acid development rate as well as syneresis percentage were reduced with increasing TGase doses meanwhile the viscosity was increased. TGase addition was also shown affecting the total lactic acid bacteria. Based on the electron microscope results, due to the formation of cross-links protein, enzyme addition caused proteins to be distributed more evenly in gel network.