The study of peroxidase and phenoloxidase from the leaves of stevia (Stevia rebaudiana) introduced to Georgia

Abstract

Phenoloxidase (EC 1.14.18.1; monophenol, dioxyphenylalanine: O₂-oxidoreductase) and peroxidase (EC 1.11.1.7; donor: H₂O₂-oxidoreductase), the oxidizing enzymes of stevia introduced to Georgia, have been studied in order to obtain a sweetener, food additive with a sharp dark color, enriched with biologically active compounds from the aforementioned plant raw material. The pH-optimums for the activity of these enzymes and other principle kinetic characteristics have been investigated. The quantitative content of polyphenolic compounds, natural substrates for phenoloxidases and peroxidases, was investigated in stevia raw material and found to be quite high, accounting for almost a third of the total amount of the extracted substance. It has been established that the stevia varieties introduced to Georgia have quite strong oxidative enzymatic systems, enabling the production of a food sweetener that is enriched with biologically active compounds and has a sharp dark color for use in the production of chocolate and other dark-colored products.