Effect of Adding Glutamine Transaminase on the Quality of Set-style Yogurt

The objective of this work was to study the difference of physical and chemical indexes and sensory indexes between set-style yogurt with TG enzyme and plain set-style yogurt (without TG enzyme) in the fermentation process. The changes of acidity, viscosity, hardness, water holding capacity and viable count of yogurt during fermentation were measured by phenolphthalein indicator method, rheometer, texture analyzer, centrifugation and plate counting method, respectively. The changes of color, taste and smell were measured by electronic eye, electronic tongue and electronic nose, respectively, and sensory evaluation was carried out. The results showed that adding 0~5 U TG enzyme per gram of milk protein, the acidity of yogurt at the end of fermentation was within the range of 71.12~73.64 oT, and there was no significant difference in the acidity of yogurt (P>0.05). During the fermentation process, the viscosity and hardness increased significantly after 3 h (P