Evaluation of fermentation kinectics of coffee infusion Kombucha

Kombucha is a millennial beverage obtained from sugared tea or infusion substrates through a controlled fermented process using a Symbiotic Culture of Bacterial and Yeast (SCOBY). Substrate diversification in kombucha production is an alternative for the development of new beverages with health promotion potential. Coffee is one of the most popular beverages consumed in the world rich in bioactive compounds, thus coffee infusion could be an alternative substrate for kombucha production. The aim of this study was to evaluate fermentation kinetics of coffee infusion kombucha. The beverages infusions were prepared with roasted and ground arabica coffee (10 %, w/v), sucrose (10 %, w/v) and SCOBY (8 %, w/v). The beverages were incubated at 25 ± 2 °C for 14 days. During fermentation days of 2; 4; 7; 9; 11 and 14, pH and soluble solids (°Brix) of the beverages were measured. Reducing sugars were quantified in sugared coffee infusions (BCA) and coffee fermented kombucha after 14 days (KC14). As results, mean value for pH varied from 5.2 to 4.3 and soluble solids from 10.4 to 9.6 °Brix. Reducing sugars for BCA and KC14 were 104 g/L and 63 g/L respectively. The pH reduction during the fermentation process might be due to the organic acids production, however, from the day 7th of fermentation no pH variation was observed. The reduction of soluble solids and 39 % lowering of reducing sugars occurred probably due to the utilization of these monosaccharides by the SCOBY during fermentation. These results show that the production of kombucha based on coffee infusion is technologically viable, since changes in the physicochemical characteristics prove the metabolic activity of the SCOBY, thus presenting another alternative for adding value to coffee and the possibility of inserting a new product on the market.