Usage of Kombucha ‘Tea Fungus’ for Enhancement of Functional Properties of Herbal Beverages

The following herbal teas were fermented with the Kombucha “tea fungus” for 7 days: Acacia arabica, Aegle marmelos root bark, Aerva lanata, Asteracantha longifolia, Cassia auriculata, Hemidesmus indicus, Hordeum vulgare, Phyllanthus emblica, Tinospora cordifolia. Microbial enumerations of the bacteria and fungi present in the broth and the tea fungal mats were carried out. At the end of the period of fermentation, the pH values ranged from 4.0 to 6.0, while the titratable acidity (TA) ranging from 2.5 to 5.0 g/mL. The TA was within the acceptable limits of consumption for all beverages. The Oxygen radical absorbance capacity (ORAC) assay indicated 5 of the fermented beverages to have statistically significant increases (P < 0.05) by the end of the period of fermentation. By day 7, the IC50 values of the α-amylase inhibitory activities ranged from 52.5 to 67.2 μg/mL, while the α-glucosidase inhibitory activity values ranged from 95.2 to 196.1 μg/mL by this time point. Overall, an enhancement of the antioxidant and starch hydrolase inhibitory potential of the seven herbal teas was observed as a result of the fermentation by addition of the tea fungus. Thus, this fermentation process could be highlighted as a novel and versatile methodology to obtain functional beverages