Production of Kombucha Using Black Mulberry and Grape Natural Syrups as Sweetener and Base of Fermentation in Green and Black Tea

The possibility of replacing sugar with grape and black mulberry syrups in the production of Kombucha and its effect on pH, acidity, polyphenols, flavonoids, antioxidant activity, glucose and organoleptic properties was investigated during 15 days fermentation. The results showed that the pH of all samples decreased significantly during fermentation. The amounts of the acidity, antioxidant activity, total phenolic and flavonoid compounds of all samples increased during fermentation period, and the highest levels of them were observed in Kombucha samples containing mulberry syrup, mixed syrup, grape syrup and control, respectively. The glucose content decreased during the fermentation process and the highest reduction of glucose was observed in samples including natural syrups. Sensory analysis revealed that although Kombucha beverages made from syrups were slightly darker with sour taste than bright control sample, but based on panelists, Kombucha containing mulberry syrup was competitive with the control sample.  The findings of this study indicate the potential of replacing 50% sugar with mulberry syrup to improve the functional Kombucha with less glucose and more amounts of antioxidants and organic acids.