Determination of some quality properties and antimicrobial activities of kombucha tea prepared with different berries

Abstract

Kombucha is a slightly sweet, acidic, carbonated, fermented beverage obtained by fermenting sugared tea (Camellia sinesis) with symbiotic bacteria. In the present study, kombucha was produced from black tea (Camellia sinensis), black grape (Vitis labrusca), black mulberry (Morus nigra), and rosehip (Rosa canina) fruits. Its physicochemical, microbiological, sensory properties and antimicrobial effects were investigated. During the fermentation, pH, Brix (%), viscosity, total antioxidant, and phenolic substance values decreased (p < 0.05). Total aerobic mesophilic bacteria (TAMB) and yeast/mold, Lactococcus/Streptococcus counts decreased, while the osmophilic yeast, acetic acid, and lactic acid bacterial counts increased (p < 0.05). The samples produced using black mulberry had the highest antibacterial activity (26.58 mm zone diameter), lowest minimum inhibitory concentration (MIC) (0.012 mg·L$^{-1}$), and minimum bactericidal concentration (MBC) (0.008 mg·L$^{-1}$) on Staphylococcus aureus. The highest antifungal activity was in the rosehip on Mucor racemosus (p < 0.05). The a* values increased during fermentation, while L* and b* values decreased. Based on the sensory analysis, black mulberry was the most preferred sample concerning all assessment criteria.