Enzymatic oxidation in wine is typically driven by oxidative enzymes from damaged tissue, such as polyphenol oxidase.

• A. True
• B. False
• C. Only occurs at high temperatures
• D. Only occurs in red wines

Answer: (A)

The main idea is that enzymatic oxidation in wine is driven by enzymes released when grape tissue is damaged. Polyphenol oxidase is a classic example: when grapes are crushed or otherwise damaged, PPO gets into the juice and, in the presence of oxygen, oxidizes phenolic compounds to o-quinones. These reactive intermediates quickly polymerize to brown pigments, contributing browning and potential off-flavors. Temperature influences the rate but isn’t a gatekeeper—enzymatic activity occurs within normal winemaking temperatures and can be accelerated by heat. This process isn’t exclusive to red wines; white wines can experience it too if tissue damage and oxygen are present. So the statement is true because enzymatic oxidation in wine is indeed driven by oxidative enzymes from damaged tissue, such as polyphenol oxidase.