Investigation of the antioxidant properties of different kombucha and their effects on some food pathogens

Aim: The study investigates the antioxidant properties of kombucha teas fermented with different plants and their antimicrobial effects against foodborne pathogenic microorganisms. The aim was to demonstrate the potential of kombucha as a functional food on a scientific basis. Material and Method: In this study, kombucha tea was prepared using ten different plants, including black, white, and green teas, as well as chamomile, echinacea, elderberry, ginseng, matcha, hibiscus, and mint, and subjected to fermentation for 15 days. The pH, acidity, TAS, TOS, and OSI values were measured in the samples. The antimicrobial activity of the kombucha teas was tested against seven different bacterial strains using the agar well diffusion method. Results: As a result of the study, significant differences were found in the biological activities of kombucha samples according to the plant species. In terms of antioxidant capacity, the highest TAS value was observed in white tea kombucha (3,258 mmol Trolox equiv. /L), followed by green tea and matcha kombuchas. The lowest TAS values were measured in chamomile, echinacea and ginseng kombuchas. In terms of oxidant capacity, the highest TOS value was found in elderberry kombucha (11,850 µmol H₂O₂ equiv. /L) and the lowest value was found in ginseng kombucha (4,860 µmol/L). According to OSI values, white tea kombucha showed the lowest oxidative stress level with 0,027, while elderberry and chamomile kombuchas showed the highest values with 0,093 and 0,090, respectively. Conclusion: Noticeable differences were observed in the biological activities of kombuchas prepared with different herbal materials. White tea, green tea and matcha showed high antioxidant capacity, while hibiscus, matcha and elderberry showed strong antimicrobial effects. It was concluded that the value of kombucha as a functional food varies significantly depending on the herbal material used.