Comparative study of yak and cow milk fermented with auxiliary cultures: Physicochemical, microstructural and flavor profiles

Fermented milk is the daily products facing many challenges, including natural flavor, good texture, and more health. In this study, the Leuconostoc mesenteroides and Saccharomyces cerevisiae were employed as the auxiliary fermenters to solve the challenge. After the fermentation, both cow fermented milk and yak fermented milk showing comprehensive fruit flavors, and the GC-MS/MS demonstrated that the generation of 19 kinds of volatile compounds including ester, ketone, aldehyde, and acid are major contributor and mainly provide fruit, flowers, and coconut flavor. Such as isoamyl acetate and ethyl caprylate, increased by 164.20 ± 8.04 µg/kg and 115.53 ± 13.49 µg/kg in ME after the addition of auxiliary fermenters. Meanwhile, the concentration of off-volatile compounds decreased or degradation by the fermentation with auxiliary fermenters, such as 3-methyl-2-butenal (roasted flavor). At the same time, the fermented milk participated with the auxiliary fermenters improve the texture, especially in firmness increasement by 1.28% and 27.7% for ME and YE, respectively. The result of scanning electron microscope also proofed that protein network was thicker with smaller gaps and larger clusters fermented by auxiliary than that of the control. The milk fermented participated with auxiliary increase the water holding capacity by 73.33% and 98.47% for ME and YE, respectively. And the total acceptance than that of the control.