Polyphenol Oxidase Enzyme (PPO)
Definition - What does Polyphenol Oxidase Enzyme (PPO) mean?
Polyphenol oxidase (PPO) enzyme is not always present in fruits and vegetables. However, when it is, it contributes to the oxidation and "browning" of fruits and vegetables.
In winemaking, it triggers the generation of darker pigments when grapes are crushed. This is especially apparent in white winemaking. This can be prevented with sulfur dioxide and by reducing oxygen contact with the wine.
WineFrog explains Polyphenol Oxidase Enzyme (PPO)
The production of polyphenol oxidase (PPO) and caftaric acid is a compound production that results in the lower level of browning in some white wines. It is more present in grapes which are infected with botrytis cinerea (noble rot).
The presence of PPO is a natural means for the degradation of organic compounds. In winemaking, it is an undesirable element, as it can cause the oxidation of wine and thus lower the quality of its flavor, aroma and health.
These PPOs are copper oxidoreductases, which exhibit cresolase and catecholase activities.
Some, if not most of the oxidative properties of polyphenol oxidase can be prevented by the use of sulfur dioxide. It can also be reduced by making sure all wine vessels are topped up or gassed with nitrogen or argon.