Certain production variables and antimicrobial activity of novel winery effluent based kombucha

Kombucha beverage was produced using effluent from clarifying the grape must. Substrate for fermentation was prepared by diluting sterilized winery effluent to 70, 50, and 30 g/L of total sugars. Fermentation lasted for nine days at 20, 25, and 30 °C. A pleasant taste kombucha was produced. The beverage was ready to drink after three days of fermentation. From 300 mL fermentation volume, more than 40 g/L of biomass was produced at maximum temperature and sugar content. Acetic acid was the acid, with a peak concentration of 14.63 g/L after nine days at 30 °C and 70 g/L. Tartaric acid originated from the grape. Oxalic acid content was higher at the lower fermentation temperature. Produced kombucha had good antimicrobial properties. Higher temperature and sugar content promote antimicrobial activity against both Gram-positive and Gram-negative bacteria. No activity against yeast was observed. Antimicrobial properties against bacteria and acetic, tartaric, and oxalic acids content were modelled using RSM. Correlation analysis showed a positive relationship between acetic and tartaric acid content and antimicrobial activity.