Abstract:
Kombucha, a fermented sugar black tea, is widely consumed due to refreshing and beneficial on human health. During fermentation process, the yeast and acetic acid bacteria are the predominant microorganisms. Thus, the aim of this research was isolated and identification of yeast and acetic acid bacteria from kombucha in three provinces of Thailand including Bangkok, Nonthaburi and Chiangmai for more effective kombucha fermentation. The results showed that 97 isolated yeast and 99 isolated acetic acid bacteria were selected, biochemical test and identified by molecular techniques. It was found that Zygosaccharomyces bailii YN403 were cultured in sweet Oolong tea medium (pH3) and showed the highest ethanol production of 4.91±0.17%. For acetic acid bacteria, Acetobacter pasteurianus AJ605 showed that exhibited the highest total acid of 1.18±0.03%. Z. bailii and A. pasteurianus were utilized to produce kombucha in difference ratio such as 3:7 4:6 5:5 6:4 and 7:3 compare to commercial kombucha. From there case, the pH values, total acidity content, total sugar, alcohol content, DPPH radical scavenging assay and sensory evaluation were 2.64-2.69, 1.12-1.35%, 47.12-49.05 g/L, 2.25-2.80% and 96.48-98%. Sensory test of clarity, colour, aroma, taste and favored, the ratio 6:4 showed highest score of taste and favored in day 7-10 than others ratio but lower than commercial kombucha tea.