Polyphenol

Bacteria

Biology

Grape wine

Biochemistry

Botany

Peroxidase

Food science

Genetics

Gallic acid

Malolactic fermentation

Polyphenol oxidase

Lactic acid

Antioxidant

Enzyme

Chemistry

Wine

Berry

Fermentation

Vitis

The activity of polyphenol oxidase (PPO) and content of phenolic compounds were followed during the maturation in two varieties of wine grapes grown in south-eastern Spain and during vinification at different sulphur dioxide concentrations. Both cresolase and catecholase activities (measured at pH 7.0 and 4.5, respectively) increased throughout the studied period and the content of phenolic compounds decreased rapidly when expressed as concentration (mg gallic acid/g total fresh weight), while when expressed as total amount per berry (mg/berry) it remained constant. During wine production, the enzyme activity was highest immediately after crushing of the fresh grapes and was not detected at the end of the fermentation process. The phenolic content also decreased during vinification to a constant level depending on the S02 level used.

Evolution of grape polyphenol oxidase activity and phenolic content during maturation and vinification