The dynamics of oxidative enzymes during the white winemaking

The aim of this paper was to monitorise the evolution of the oxidative enzymes activity during the process of winemaking from white grapes. The second objective was to evaluate the browning capacity of the grape must during the alcoholic fermentation stage and in the resulting wine. During the alcoholic fermentation,the activity of the oxidative enzymes was reduced, thus the enzymatic activity of the peroxydase decreased by approximately 60% of the initial activity, the enzymatic activity of the tyrosinase decreased by approximately 40% of the initial enzymatic activity and the enzymatic activity of the laccase decreased by approximately 40% of the initial enzymatic activity. The activity of the oxidative enzymes in wines diminished progressively after three months of wine aging.The enzymatic activity of the tyrosinase decreased by 25-60% of the initial enzymatic activity. The enzymatic activity of the peroxydase was reduced appreciatively by 10% of the initial enzymatic activity.The enzymatic activity of the laccase reached the value 0 at three months after the wine had been obtained. During the alcoholic fermentation stage the values of the PFO and IB indices increased and during the evolution of the wine (after 3 months) the values of the PFO and IB indices decreased.