Novel kombucha beverages with antioxidant activity based on fruits as alternative substrates

Abstract

The consumption of kombucha drinks has remarkably grown during the last decade and, besides traditional ingredients such as tea leaves, alternative raw materials with interesting functional properties are being proposed. The aim of this study was to obtain alternative kombuchas enriched in phenolic compounds and with a high antioxidant activity using fruits instead of tea leaves, and to determine the optimal fermentation time. The fruit-based kombuchas were prepared using cherry, plum, apricot, strawberry, persimmon, grape, orange, or pomegranate and three different microbial consortia (SCOBYs/SCs). The pH, carbohydrate, ethanol, and phenolic levels, and in vitro antioxidant capacity were determined along the fermentation process (21 days). The obtained products showed safe pH values (2.5–4.2) and suitable ethanol levels (<1.2%). Their carbohydrate content was almost half that in commercial tea kombucha. The activity of fermentative microorganisms increased total phenolic content (TPC) and radical scavenging capacity (TEAC) in all preparations, and differences were found depending on the SC used. Maximum TPC and TEAC values were observed in the strawberry kombucha (up to 13.7 mg/100 mL and 2.05 μmol/mL, respectively). The results showed that fruits, mainly strawberries, could be used to obtain alternative kombucha drinks with high in vitro antioxidant activity.