Use of a Minimal Microbial Consortium to Determine the Origin of Kombucha Flavor

Abstract

Microbiological, chemical, and sensory analyses were coupled to understand the origins of kombucha organoleptic compounds and their implication in the flavor of the kombucha beverage. By isolating microorganisms from an original kombucha and comparing it to monocultures and cocultures of two yeasts (Brettanomyces bruxellensis and Hanseniaspora valbyensis) and an acetic acid bacterium (Acetobacter indonesiensis), interaction effects were investigated during the two phases of production. 32 volatile compounds identified and quantified by Headspace-Solid Phase-MicroExtraction-Gas Chromatography/Mass Spectrometry (HS-SPME-GC/MS) were classified according to their origin from tea or microorganisms. Many esters were associated to H. valbyensis, while alcohols were associated to both yeasts, acetic acid to A. indonesiensis, and saturated fatty acids to all microorganisms. Concentration of metabolites were dependent on microbial activity, yeast composition, and phase of production. Sensory analysis showed that tea type influenced the olfactive perception, although microbial composition remained the strongest factor. Association of B. bruxellensis and A. indonesiensis induced characteristic apple juice aroma.

Evaluation of microbiota-induced changes in biochemical, sensory properties and volatile profile of kombucha produced by reformed microbial community

“…Therefore, yeast-bacteria fermentations were begun at yeast-to-bacteria ratios of 2:3 ( Nguyen et al, 2015 ). In addition, when yeast and bacteria are inoculated at the same rate, the number of acetic acid bacteria decreases due to restricted oxygen access ( Tran et al, 2022 ). Yeast counts were higher than bacteria counts on day 14 for all fermentations except Bb - Ks and Bb - Ap ( Fig.…”

“… Tran et al (2022) identified the volatile compounds produced during kombucha fermentation by two yeasts isolated from kombucha ( B. bruxellensis and H. valbyensis ) and reported that saturated fatty acids were the signature metabolites of those yeasts. However, in the present study, those fatty acids could not be detected in any of the Bb fermentations.…”

“…In particular, isovaleric acid and phenyl ethyl alcohol were only formed in yeast - bacteria fermentations. This suggests that microbial diversity influences volatile compounds and therefore, can influence consumer taste by altering the sensory properties of the product ( Tran et al, 2022 ). Acetic acid, as one of the important metabolites found in kombucha, was clearly observed in cocultures with Ap.…”

“…Acetic acid, as one of the important metabolites found in kombucha, was clearly observed in cocultures with Ap. Alcohols and esters, which have significant sensory effects on fermented products, are commonly known as yeasts' key metabolites ( Tran et al, 2022 ). Such metabolites were associated with Db in the present study.…”

“…The yeast species Brettanomyces bruxellensis , Hanseniaspora valbyensis , Zygosaccharomyces bailii , Zygosaccharomyces parabailii and bacterial species Acetobacter indonesiensis , Komagataeibacter hansenii , Gluconobacter oxydans , Liquorilactobacillus nagelii , and Novacetimonas hansenii were utilized in some previous studies of microbial communities investigating yeast-bacteria interactions for kombucha fermentation ( Ferremi Leali et al, 2022 ; Savary et al, 2021 ; Tran et al, 2020 ; Tran et al, 2022 ). However, studies of yeast-yeast or bacteria-bacteria interactions in kombucha production are not available in the literature.…”