부산대학교 도서관

Kombucha is an acidic beverage, produced by fermenting sugared black tea decoction with both yeasts and acetic acid bacteria. In this study, we evaluated effects of three cultivation modes, including static fermentation (SF), two stage fermentation: static and agitated conditions (TSF-S, TSF-A), and upflow fixed bed fermentation (UFBF) on kombucha preparations. Results showed that counts of yeasts and acetic acid bacteria maintained constant throughout kombucha fermentation under UFBF, and final concentrations (at day 15) of these starters were 5.8 and 5.9 log (cfu/ml), respectively. TSF-A mode favored multiplications of yeasts and acetic acid bacteria. Kombucha starters showed the highest rates of sugar consumptions under UFBF and final glucose and fructose contents in the broth were 0.06% and 0.3%(w/v), respectively. The highest levels of acetic acid (2.5%, v/v; day 15) and ethanol (6.36%, v/v; day 15) were detected in the broth under SF and UFBF, revealing that these modes were suitable for growth of both acetic acid bacteria and yeasts, respectively. UFBF mode might be helpful for increasing kombucha fermentation efficiency, but the medium reservoir should be adequately aerated to aid acetic acid bacteria growth, and decrease ethanol production by inhibiting the alcohol fermentation.