Determinação eletroanalítica e espectrométrica de fenóis totais e atividade antioxidante de kombuchas

Abstract

Introduction: Kombucha is an ancient beverage made from green or black tea and saccharides, fermented by a microbial culture (SCOBY). This functional beverage boasts health benefits such as improved gut microbiota function, hepatoprotection, and inhibition of amyloid fibers. It contains antioxidant bioactives, including catechins, ascorbic acid, B vitamins, and other polyphenolic compounds, all found in kombucha. Methods: The antioxidant activity of kombucha samples was evaluated using electroanalytical and spectrophotometric techniques such as Differential Pulse Voltammetry (DPV) and Square Wave Voltammetry (SWV), with results obtained by traditional spectrometric methods such as Folin Cicateou (FC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and Fluorescence Recovery After Photobleaching (FRAP). Samples of kombucha probiotic beverage were fermented for 7 to 14 days at a controlled temperature (28 ± 2ºC). Results and Discussion: A linear curve for catechin was created with a range of 10.00 to 60.00 µM, with a detection limit of 0.13 µM and a quantification limit of 0.39 µM for the Cordia Superba enzymatic biosensor. In parallel, the antioxidant activity of aliquots of kombucha samples diluted in phosphate buffer pH 7.0, 1:10, was evaluated for analytical reading, obtaining VPD results, where anodic peaks characteristic of the electroactive compounds present were observed. Conclusion: The results indicated that electrochemical methods offer greater sensitivity and specificity in determining the antioxidant capacity of kombucha when compared to traditional spectrophotometric activities. DPV and SWV techniques also proved to be effective tools for inferring the bioactive composition and functional potential of these beverages.