Construction of synthetic microbial community to modulate the sensory quality in kombucha fermentation

This study focused on screening lactic acid bacteria (LAB) to construct a synthetic microbial community (SMC) for fermenting kombucha and the quality was compared with that of traditionally fermented kombucha (TK), which utilized a SCOBY as the starter culture. Through a process of isolation, screening, and fermentation performance evaluation, a LAB strain was successfully isolated from the traditionally fermented kombucha broth. The strain was identified and designated as Lacticaseibacillus paracasei XT-5. A SMC including Saccharomyces cerevisiae Y-01, Wickerhamomyces anomalus ZX-1, L. paracasei XT-5 and Komagataeibacter oboediens CGMCC 22548 with an inoculation ratio of 0.75%:0.75%:2%:1%, was constructed for kombucha fermentation. Compared to the TK group, the kombucha fermented by SMC (SK group) showed a 1.35-fold increase in organic acids and a 6.57-fold increase in free amino acids, but a 0.84-fold decrease in soluble protein. Color analysis indicated a higher red intensity in the SK group. Furthermore, volatile compound analysis identified 27 in SK group and 25 flavor in TK group, respectively. OPLS-DA analysis revealed that ethanol, ethyl acetate, acetic acid, 3-methyl-1-butanol, ethyl caprylate, isoamyl acetate, and phenethyl alcohol made significant contributions to the characteristic flavor profile of kombucha. Electronic tongue analysis indicated no significant differences in the overall sensory profiles between the SK and TK groups, suggesting that the SMC successfully captured the core sensory attributes of traditional kombucha. These findings suggest potential applications in industrial production for standardized kombucha production.