Changes in content of organic acids and tea polyphenols during kombucha tea fermentation

Abstract

Kombucha tea is a fermented tea beverage produced by fermenting sugared black tea with tea fungus (kombucha). Tea polyphenols which includes (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCG) and theaflavin (TF) have been reported to possess various biological activities. The present study focused on changes in content of organic acid and tea polyphenols in kombucha tea prepared from green tea (GTK), black tea (BTK) and tea manufacture waste (TWK) during fermentation. Concentration of acetic acid has reached maximum up to 9.5 g/l in GTK on 15th day and glucuronic acid concentration was reached maximum upto 2.3 g/l in BTK on 12th day of fermentation. Very less concentration of lactic acid was observed during the fermentation period and citric acid was detected only on 3rd day of fermentation in GTK and BTK but not in TWK. When compared to BTK and TWK very less degradation of EGCG (18%) and ECG (23%) was observed in GTK. TF and thearubigen (TR) were relatively stable when compared to epicatechin isomers. The biodegradation of tea catechins, TF and TR during kombucha fermentation might be due to some unknown enzymes excreted by yeasts and bacteria in kombucha culture.