Polyphenols in kombucha: Metabolomic analysis of biotransformations during fermentation

Abstract

Kombucha is a non-alcoholic beverage made of sugared tea that is transformed by a symbiotic consortium of yeasts and bacteria. This beverage is increasingly produced at industrial scale, but its quality standards remain to be defined. Metabolomics analysis was carried out using FT-ICR-MS to understand the chemical transformations induced by the production phases and the type of tea on the non-volatile compounds of kombucha. Of the two production phases, the first phase of acidification in open vessel was the most impactful on molecular diversity, but tea type mainly influenced the global composition in polyphenol profiles. Black tea polyphenols were more impacted by microbial activity compared to green tea polyphenols. Independently from tea type, the first phase was also characterized by the release of gluconate from acetic acid bacteria metabolism. Gallate was also released and probably originated from the hydrolysis of ester bounds located in polymeric flavan-3-ols. The biotransformation of antioxidant polyphenols could positively impact their bioavailability for the consumer.