Enzymes are natural protein catalysts that facilitate and increase the rate of chemical reac­tions. Enological enzymes are used to accelerate natural reactions that would otherwise oc­cur slowly in wine. Enzyme use can promote fruit and spice characters while reducing sulfur off-odors, herbaceous and mineral characteristics. For most enzymes, the addition to grapes as soon as possible helps with extraction of aroma precursors, reduces maceration time and helps increase juice yield.