Production and Analysis of Kombucha : A Black Tea based Functional Beverage

Kombucha is a sweet, slightly acidic, low-alcoholic functional beverage produced by fermentation of tea using Symbiotic culture of bacteria and yeast (SCOBY). It can be considered as an alternative of carbonated soft drinks because it contains lesser calories and sugar content and is having other health promoting properties. Though tea is widely used as a beverage but its fermentation to produce a functional beverage is not well exploited in India. Home-brewing of the beverage has become more common in developed countries because of the growing recognition of kombucha as a "healthy" product. Therefore, a standard protocol for the production of a safe fermentation process with significant health value is desirable. In the present study, Black tea based Kombucha is prepared using different concentrations of tea (5-15 g/L) and sugar (40-80 g/L). Optimum concentration of tea and sugar was obtained by applying Central Composite Rotatable Design (CCRD) under Response Surface Methodology (RSM) using 'Design Expert 13' for getting the product with maximum antioxidant activity. Fermentation was carried out by varying inoculum level from 5-15% and it was observed that 5% inoculum level was optimum for characteristic fermentation. Periodic changes in pH, TSS, titrable acidity, total sugars, reducing sugars, antioxidant activity, total phenolic content, vitamin C content and alcohol content was recorded for all the thirteen formulations suggested by RSM during fermentation period of 7 days. Microbiological and sensory evaluation of all the combinations was done and selected two combinations (Beverage 6 with Tea @ 5 g/L and Beverage 13 with Tea @ 15 g/L, both having Sugar @ 80 g/L) received a score of 8.14 and 7.90, respectively.