Influence of starter cultures on the antioxidant activity of kombucha beverage

This paper investigates the influence of starter cultures, obtained from kombucha isolates, on the antioxidant activity of kombucha beverages. Three starter cultures were used as follows: (1) mixed culture of acetic bacteria and Zygosaccharomyces sp. (SC1); (2) mixed culture of acetic bacteria and Saccharomyces cerevisiae (SC2); as well as (3) native local kombucha. The starter cultures were added to black and green tea sweetened with 7% of sucrose. Fermentation was carried out at 28 °C for 10 days. Antioxidant activity to hydroxyl and DPPH radicals was monitored. Kombucha beverage on black tea has shown the highest antioxidant activity to both types of radicals with starter SC1, while the green tea beverage has shown the highest activity with native kombucha. The main reason for the different antioxidant activities, beside tea composition, was ascribed to differing production of both vitamin C and total organic acids in the investigated systems.

Research highlights
► Starters obtained from kombucha isolates can be used for successful fermentation.
► Different starters formed from kombucha isolates affect antioxidant activity (AA).
► Mix of Zygosaccharomyces sp. and acetic bacteria caused the best AA on black tea.
► Native kombucha provided the best results on green tea.
► Total acids and vitamin C greatly correlate the antioxidant activity in both teas.