Conclusion
Tea polyphenols (EGCG, EGC, ECG, EC, TF and TR)
and organic acids are believed to be the active ingredients
in kombucha tea that possess a range of beneficial effects.
The present study examined the changes in content of tea
polyphenols and organic acids along with pH, protein
and microbial content in green tea, black tea and tea manufacture
waste tea during kombucha fermentation. Acetic
acid and glucuronic acid were reached maximum on 15th
(in GTK) and 12th (in BTK) day of fermentation respectively.
The present study is the first to report the stability
of tea polyphenols during kombucha fermentation. Results
showed that TF and TR were relatively stable than epicatechin
isomers during kombucha fermentation. Epicatechin
isomers were degraded upto 9th day of fermentation and a
marked increase on 12th day was observed. Interestingly,
content of EGC and EC on 12th day was higher than the
initial concentration. Biotransformation of EGCG to
EGC and ECG to EC by enzymes excreted by microorganisms
in kombucha culture and release of catechins from
acid-sensitive cells could be the reason for the increased
concentration of tea polyphenols on 12th day of fermentation.
Identification and characterization of extra cellular
key enzymes responsible for the degradation of epicatechin
isomers, TF and TR is in progress. The present study also
revealed the possibility of using tea waste material for manufacturing
the kombucha tea beverage.