If you've ever read the ingredients list on a jar of jam or jelly, you've probably seen the phrase "fruit pectin." Pectin is a substance in fruit that binds cells together, helping to form the fruit skin. Winemakers use pectic enzymes to break down the cell walls, break the grape skins apart and extract more juice from the grape. Pectic enzymes are also used to clarify the wine and remove cloudiness or "haze" caused by leftover pectins.
Enzymes can also be used to modify the flavor and aroma of the finished wine. An enzyme called lysozyme (found naturally in egg whites and human tears, among other things!) is sometimes used to control the process of malolactic fermentation, which takes place when bacteria convert the grape's natural, tart-tasting malic acid into milder, softer tasting lactic acid.