Abstract: The objective of this study was to analyze how different fermentation methods can affect the fermentation profile of kombucha in terms of its flavor, fermentation yield (total acid/sugar consumption) and sensory evaluation. The variable factors considered included black tea type, tea extraction modes, concentrations of sugar and tea and inoculum size of starter culture. The optimized conditions for the best quality of kombucha were obtained after adding 0.5% mellow black tea to boiling water and keeping it at room temperature for 15 min, followed by the addition of 7% sugar and 8% komucha starter culture. Finally, the fermentation process was carried out at 30 ℃ for 10 days. After fermentation the broth was clear with pale yellow color, and sweet and moderately sour taste. A considerable change in flavor profile was observed before and after the fermentation under the optimized conditions. A total of 19 volatile aroma compounds were identified including 7 alcohols, 6 esters, 4 acids, 1 phenol and 1 hydrocarbon. The contents of alcohols, acids and esters were 25.09%, 46.40% and 15.91%, respectively.

Key words: kombucha, black tea, fermentation, flavor