Polyphenols and antioxidant activities of kombucha beverage enriched with coffeeberry® extract

Abstract

Kombucha is a traditional beverage obtained by fermenting sweetened black tea with tea fungus, which represents a consortium of acetic acid bacteria and yeasts. Also, CoffeeBerry® products, derived from the whole fruit of the coffee plant, are valuable ingredients with nutritional and health-enhancing potential. Samples of fermentation broths enriched with CoffeeBerry® extract and traditional Kombucha were analysed. The fermentation was performed in a bioreactor at 28±1 °C for nine days. The results showed that the CoffeeBerry® extract contributed to a faster fermentation of cultivation medium. Some individual polyphenolic compounds and catehins in fermentation broth samples were identified and quantified by high performance liquid chromatography (HPLC). Among the bioactive compounds present in investigated samples obtained during Kombucha fermentation of the sweetened black tea enriched with CoffeeBerry® extract, chlorogenic acid (188.94-458.56 μg/mL) was the predominant. The antioxidant activity of investigated samples was tested by measuring their ability to scavenge DPPH and reactive hydroxyl radicals by electron spin resonance (ESR) spectroscopy. The scavenging activities on DPPH and hydroxyl radicals were increased with the duration of fermentation. IC50 values for Kombucha fermentation broth enriched with CoffeBerry®, based on DPPH and hydroxyl radical scavenging activities, were in the ranges 26.33- -170.13 and 11.33-102.22 μL/mL, respectively.