Enzyme

Any of numerous protein molecules produced by living organisms (including yeast) and functioning as catalysts in biochemical reactions. Despite their derivation from living materials, are not living organisms themselves. Enzymes emerge intact from the catalytic reactions they produce and are denatured (rendered inactive) by pH extremes and high temperatures. Usually, an enzyme acts only on a specific molecule (substrate), so an enzyme that acts upon pectin will not act upon starch. In winemaking, most of the essential enzymes are produced by yeast, but some are not and must be introduced by the winemaker. Some of the more important enzymes that find use in winemaking are:

• Amylase - An enzyme which catalyzes the hydrolysis of starch into maltose and dextrin.
• Cellulase - Any of several enzymes which catalyze the hydrolysis of cellulose.
• Invertase - An which that catalyzes the hydrolysis of sucrose into an equal mixture of glucose and fructose.
• Lactase - An enzyme which catalyzes the hydrolysis of lactose into glucose and galactose.
• Lipase - Any of a group of enzymes which catalyze the hydrolysis of triglycerides into glycerol and fatty acids.
• Maltase - An enzyme which catalyzes the hydrolysis maltose to glucose.
• Pectinase - An enzyme which catalyzes the hydrolysis of pectin to pectic acid and methanol.