Physicochemical properties, volatile compounds and basic spherification of hibiscus ( <i>Hibiscus sabdariffa L.)</i> kombucha beverage

Kombucha is a fermented beverage with a slightly acidic taste, flavor, and natural carbonation. It has gained popularity due to its health benefits. Traditional kombucha is prepared by fermentation of black tea and sucrose. Today, kombucha products do not have a standard composition and there is a growing demand. Therefore, the purpose of this research was to produce kombucha with hibiscus and two different sweeteners (apple juice concentrate and sucrose), to examine physicochemical properties, ethanol and vitamin B12 contents, to identify volatiles, and to study its compatibility in spherification. Fermentation resulted in a pH drop. Decrease in brix of kombucha with apple juice concentrate was seen whereas brix of kombucha with sucrose did not change. While density and fermentation rate of apple juice concentrate containing sample were higher than those of the sucrose containing one, beverage yields were similar. Negligible color changes were encountered during fermentation. Ethanol, vitamin B12, and carbon dioxide levels were determined as 1.08-1.12 g/L, 0.054-0.071 µg cyanocobalamin/100 g, and 0.40-0.43 g/L, respectively. Decanoic acid, octanoic acid, and lauric acid were the major volatiles. Kombucha spheres with apple juice concentrate had higher diameter and weight whereas spheres with sucrose had more uniform surface and less color change.