Effects of Lactobacillus fermentum HY01 on the quality characteristics and storage stability of yak yogurt

Lactobacillus fermentum HY01 is a probiotic strain screened from traditional yak yogurt, which can effectively relieve enteritis and constipation. This study aimed to evaluate the effects of HY01 as an adjunct starter on the quality and storage of yak yogurt. A to-tal of 36 main volatile flavor substances were detected in all samples. In particular, more aldehydes, esters, and alcohols were detected in yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter MY105 (including Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus). The rheological results showed that the yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter MY105 had higher apparent viscosity and lower tan delta value compared with compared with traditional yak yogurt, yak yogurt with only L. fermentum HY01, and cow yogurt with L. fermentum HY01 and starter MY105. Meanwhile, the conjugated linoleic acid in the yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter was significantly higher than those in the HY01 group or the yogurt starter group alone. After 28 d of storage at 4 degrees C, the number of HY01 in the yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter was still higher than 107 cfu/mL, its acidity was lower than 110 degrees T, and its syneresis was the lowest. The results indicated that L. fermentum HY01 could improve the flavor, texture, and storage properties of yak yogurt.

Automated summary

Lactobacillus fermentum HY01 improves the flavor, texture, and storage properties of yak yogurt. The yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter MY105 has higher viscosity, lower tan delta value, and higher conjugated linoleic acid content.