Antioxidants are responsible for many beneficial health effects and are highly present in natural products, such as kombucha. Biosensors’ development targeting antioxidants and phytomarkers are an active research field. This work aimed to propose a voltammetric polyphenolxidase (Cordia superba) biosensor for catechin and total phenolic compounds quantification in kombucha samples. Optimizations were performed on the biosensor of Cordia superba to improve the accuracy and selectivity, such as enzyme–substrate interaction time, analytical responses for different patterns and signal differences with the carbon paste and modified carbon paste electrode. Kombucha probiotic drink samples were fermented for 7 to 14 days at a controlled temperature (28 ± 2 °C). A linear curve was made for catechin with a range of 10.00 to 60.00 µM, with a limit of detection of 0.13 µM and limit of quantification of 0.39 µM. The biosensor proposed in this work was efficient in determining the patterns of phenolic compounds in kombucha.
