Effects of medium variation and fermentation time towards the pH level and ethanol content of Kombucha

Kombucha is one of the traditional fermented drink and known as health drink due to its claimed therapeutic efficacy. Kombucha is commonly prepared by sweetening black tea with white sugar and fermented using a bactocellulosic culture of acetic acid bacteria and yeasts. Ethanol and acid production is a part of the fermentation process and too much ethanol and acids are harmful. Nowadays, alternative carbon sources and different types of teas are also being used by home brewers and Kombucha manufacturers but the variation of its ethanol and acid content with respect to change in the fermentation medium is less known. Therefore, this study characterized the pH level and ethanol content of Kombucha by varying the carbon sources (white sugar, Kelulut honey and jaggery) in black and green tea media over a period of 7 days, 14 days, 28 days and 60 days of fermentation. Ethanol content was tested using dichromate assay and pH was estimated using an electronic pH meter. In this study, it was found that all samples were acidic with pH ranging between 2.9 – 4.5 at all fermentation periods and pH levels drop as the period of fermentation was increased. Except for honey, the ethanol content of other combination increased between 0.6% –2.75%. Hence, our data indicated that the changes in fermentation medium and period play important roles in determining the properties of this beverage. The data collected provides useful guide to prepare the Kombucha with predetermined properties.