Abstract:
Transglutaminase (TG) of 1, 2, 3 U/g protein were added to goat milk and incubated at 40 ℃ for 2 h to prepare set goat milk yogurt. The effects of TG addition on the quality of set goat milk yogurt stored for 1, 7, 14 and 21 d were studied, including acidity, texture properties, water holding capacity, lactobacillus number, flavor substance contents and sensory characteristics. The results of physical and chemical properties showed that TG addition did not influence the acidity and elasticity of the yogurt compared with the control sample during storage, while the hardness, viscosity and water holding capacity of the TG treated yogurt were significantly improved. Meanwhile, TG addition was able to inhibit the formation of acetaldehyde and diacetyl in set goat milk yogurt, but had no effect on the growth of Lactobacillus bulgaricus and Streptococcus thermophilu. The results of microscopic structure of set goat milk yogurt showed that TG treatment was beneficial for the formation of a densified three-dimensional network structure, and could enhance the sensory characteristics and mouthfeel of the set goat milk yogurt. Our finding confirmed that TG addition had positive effects on the quality of set goat milk yogurt during storage.
