谷氨酰胺转氨酶浓度对搅拌型酸羊乳贮存期品质的影响

Effect of transglutaminase concentration on the quality of stirred goat yogurt during the storage

为改善搅拌型酸羊乳的品质,采用谷氨酰胺转氨酶(transglutaminase,TG)(浓度为1、2、3 u/g蛋白)处理山羊乳,发酵制备搅拌型酸羊乳,研究其贮存期pH、黏度、持水性、风味物质、乳酸菌的变化,并采用SDS-PAGE电泳分析TG处理羊乳后乳中蛋白质的交联程度。结果表明,TG处理制备的搅拌型酸羊乳在贮存期的pH明显高于对照组;搅拌型酸羊乳在贮存期间的黏度和持水性明显增大,且随着TG浓度增大,效果越明显;搅拌型酸羊乳贮存期间的乙醛和丁二酮的含量逐渐降低,随着TG浓度越大,降低越明显;TG处理对搅拌型酸羊乳贮存期间嗜热链球菌有显著性的抑制作用,且随着TG浓度的增加,嗜热链球菌的含量越低,然而TG处理对保加利亚乳杆菌无明显影响;SDS-PAGE电泳显示,TG处理羊乳后,κ-酪蛋白和α-乳白蛋白发生明显交联,这有利于酸乳凝胶的稳定性。

To improve the quality of stirred goat yogurt and transglutaminase （TG） at 3 different concentration levels treatment （1, 2, and 3 units per gram of protein （u/g））. Its effect on yogurt quality in terms of protein crosslinking degree, pH, viscosity, water holding capacity, flavor and viable lactic acid bacteria （LAB） have been studied. The protein crosslinking degree was analyzed by SDS-PAGE electrophoresis. The SDS -PAGE result re- vealed the increase of cross-linkage of kappa-casein and alpha - lactalbumin with TG treatment, which was beneficial for yogurt stability. The pH, viscosity and water holding capacity were significantly higher and the effect were more obvious with increasing TG concentration. During storage, the acetaldehyde and diacetyl concentration decreased gradually. TG treatment inhibited Streptococcus thermophilus＇s growth during storage. As TG concentration increases, the effect was more significant. However, TG had no obvious effect on Lactobacillus bulgaricus.