Characteristics of Kombucha Fermentation from Different Substrates and Cytotoxicity of Tea Broth

Abstract

Kombucha is made from sweetened tea fermented by a symbiotic culture of bacteria and yeast consumed worldwide because of its potentially beneficial effects on health. However, there are only few studies on the safety of kombucha consumption that will establish it as a functional beverage. The present study compared, pH, temperature and sugar content of different tea mixtures of black or green tea as nitrogen sources and white and brown sugar as carbon sources in a 30-day fermentation period. A marked decrease in pH was observed throughout fermentation with Green tea-White (GW) sugar mixture showing the lowest recorded pH value of 2.37 on the 14th day of fermentation. Temperature is essential in the fermentation process and thus maintained at ambient 29±1°C. Black and green teas with white sugar (7°Brix) showed to have higher sugar level compared to tea mixtures with brown sugar (5°Brix). Brine Shrimp Lethality Assay was carried out to determine cytotoxicity of kombucha. The four substrate combinations have very low LC50 values with Black tea-Brown sugar (BB) mixture showing to have the lowest in both acute and chronic effects (0.073 ppm and 0.101 ppm, respectively). This indicates safety of kombucha for consumption.