Oxygen-induced enzymatic and chemical degradation kinetics in wine model solution of selected phenolic compounds involved in browning

Hydroxycinnamic and hydroxybenzoic acids are phenolic compounds that, upon oxidation, intensify browning, thus compromising the organoleptic quality of musts and white wines. This process is enhanced by the presence laccase, which is present in grapes after Botrytis cinerea infection. The aim of this study was to evaluate the kinetics of enzymatic and non-enzymatic degradation and browning of 15 phenolic compounds. Generally, hydroxycinnamic acids are more prone to degradation and browning reactions than hydroxybenzoic acids. The substituents present in the aromatic ring are key for determining their reaction rate. Indeed, the presence of both hydroxyl and methoxy substituents on the aromatic ring appears to facilitate enzymatic degradation in all the compounds studied. On the other hand, browning did not display a direct correlation with the degradation rate of the phenols. Finally, the chemical structure features of phenols were a reliable predictor of both browning and degradation rates.