添加酪蛋白水解肽改善酸乳的加工特性

Adding Casein Hydrolytic Peptides to Improve the Processing Characteristics of Yogurt

向牛乳中添加不同含量菠萝蛋白酶酪蛋白水解肽(0.1%、0.3%、0.5%),测定酸乳发酵及冷藏过程中理化、微生物和风味指标变化。结果表明,添加酪蛋白水解肽(casein hydrolytic peptides,CHP)加快了酸乳发酵后期pH值下降,缩短发酵时间;CHP添加量为0.1%时发酵时间较对照组缩短了34 min。微流变测定表明,添加CHP降低了发酵后期酸乳的弹性指数(elasticity index,EI)和流动性指数(fluidity index,FI),但宏观黏度指数(macroscopic viscosity index,MVI)有所升高。扫描电镜图像显示,各组酸乳样品均呈多孔网状结构,适量添加CHP(0.1%)可以改善酸乳的胶体结构,使酸乳网络结构更致密均匀。酸乳冷藏期间,添加CHP可以提高发酵剂菌株的活菌数,一定程度地促进酸类、醛类和酮类等风味化合物的形成,添加0.3%的CHP降低了酸乳EI;随着CHP添加量的增加(0.3%、0.5%),酸乳的硬度及胶着性逐渐下降,但对持水力、内聚性及黏性无明显影响。本研究为CHP在酸乳加工中的应用及产品品质和功能性提升提供技术参考。

Yogurt was prepared from raw milk added with peptides from bromelain hydrolyzed casein at different concentrations(0.1%,0.3%and 0.5%),and the changes in physicochemical,microbial and flavor characteristics of yogurt during fermentation and cold storage were determined.The results showed that adding casein hydrolytic peptides(CHP)accelerated the pH decline during the late fermentation period,and reduced the fermentation time of yogurt.When 0.1%CHP was added,the fermentation time was reduced by 34 minutes compared to the control group.Microrheological measurement showed that adding CHP decreased the elasticity index(EI)and fluidity index(FI),but increased the macroscopic viscosity index(MVI)of yogurt during the late fermentation period.Scanning electron microscopy showed that the yogurt samples in each group had a porous network structure.Proper addition of CHP(0.1%)improved the colloid structure and made the network structure of yogurt more compact and uniform.During the cold storage of yogurt,adding CHP increased the count of viable starter bacteria,and promoted the formation of flavor compounds such as acids,aldehydes and ketones,and adding 0.3%CHP reduced the EI value of yogurt.With increasing addition of CHP from 0.3%to 0.5%,the hardness and adhesiveness of yogurt decreased gradually,but water-holding capacity,cohesiveness and viscosity did not significantly change.The results of this study provide technical references for the application of CHP in yogurt processing and the improvement of product quality and functionality.