Effect of transglutaminase and buffalo milk incorporation on textural parameters and starter cultures viability of strained yogurt

The popularity of strained yogurt has risen worldwide in recent years because of factors such as the product’s extended shelf life and its easy handling and transport. The texture of strained yogurt is an important characteristic which determines the acceptability of the product. Transglutaminase enzyme (TG) is an applicable approach to improve textural characteristics of food products thru formation of isopeptide bonds between proteins. Furthermore, by incorporating buffalo milk in the product formulation, a strained yogurt with a denser and creamier texture could be produced. The aim of the present study was therefore to scrutinize the effect of TG enzyme treatment on textural characteristics of strained yogurt prepared from a mixture of cow and buffalo milk. Strained yogurt samples were produced with different amounts of buffalo milk replaced with cow milk (0, 25, 50, 75 and 100% v/v) and using TG enzyme (0 and 0.015% w/v) and evaluated during 21 days of storage at the refrigerator temperature (4°C). Generally, the amount of texture parameters increased with increasing the concentration of TG enzyme and buffalo milk replacement. With the passage of storage time, hardness and adhesiveness increased and cohesiveness decreased significantly (p < 0.001). Among the variables, only storage time had a significant effect on survival rate of lactic acid bacteria; with passage of storage time, their survival rate decreased significantly (p < 0.001). In conclusion, it was found that by using TG enzymatic treatment (0.015%) and 100% buffalo milk, it is possible to produce a strained yogurt with the best textural and sensorial characteristics.