Effects of Fermentation Time and Temperature on the Physicochemical Quality of Kombucha

Kombucha is a fermented tea beverage produced through the metabolic activity of a symbiotic culture of bacteria and yeasts (SCOBY). Although consumer demand for kombucha has increased substantially, the influence of fermentation conditions on product quality remains insufficiently understood. This study evaluated the effects of fermentation temperature and time on the physicochemical properties of kombucha. A total of 20 L of kombucha was prepared using black tea (10 g/L) and sucrose (70 g/L). After filtration, the mixture was adjusted to pH 4.14 and inoculated with SCOBY. Fermentations were conducted at three temperatures (23, 25, and 28 °C) and at three time points (7, 11, 15 days). Following fermentation, pH, viscosity, soluble solids (°Brix), titratable acidity, color, and concentrations of lactic and acetic acids were quantified. The main results showed that pH decreased progressively with increasing fermentation temperature and time (from 3.47 at 23 °C/7 days to 2.96 at 28 °C/15 days). Concentrations of lactic and acetic acids increased with fermentation time, consistent with fermentation progression. Response surface modeling (RSM) indicated nonlinear interactions between time and temperature for pH and viscosity. Overall, the results identified fermentation parameters that enhanced desirable kombucha attributes, providing a scientific basis for formulation and process optimization in commercial production.