Electrochemical Alternative for Evaluating Antioxidant Capacity in Kombuchas

Kombucha is a millennia-old beverage crafted from green or black tea and saccharides and fermented with a symbiotic culture of bacteria and yeast (SCOBY). This functional drink boasts health benefits, such as improved intestinal flora function, hepatoprotection and inhibition of amyloid fibers. It contains bioactive antioxidants, such as catechins, ascorbic acid, vitamins and other polyphenolic compounds. With kombucha’s rising popularity, the Food and Drug Administration (FDA) has implemented control procedures to ensure the quality and safety of this food product. Due to the antioxidant properties of the major bioactive compounds in kombucha, feasible and low-cost electroanalytical methods emerge as promising alternatives. The objective of this study was to evaluate the voltammetric behavior of kombucha samples to establish and compare their redox profiles and antioxidant activities. Thus, 18 kombucha samples were used, comprising commercial samples and samples prepared in the laboratory from different SCOBYs purchased from different countries, and analyzed by differential pulse voltammetry (DPV) and square wave voltammetry (SWV) on a carbon paste electrode (CPE). The electrochemical index (EI) values determined from the samples were used to establish their antioxidant activities. The EI values were also compared with spectrophotometric data from Folin–Ciocalteu (FC) and Ferric Reducing Antioxidant Power (FRAP) assays.