Polyphenol oxidase activity of Vitis vinifera c.v. cardinal, muscat and alfons during growing periods

In this study, we attempted to determine the amount of protein and polyphenol oxidase activity of Vitis vinifera c.v., "Cardinal", "Muscat" and "Alfons" during the growing period collecting samples at different dates: budding, immature grape, veraison and ripening. Generally it was observed that polypenol oxidase activity varied, depending on the varieties of Vitis vinifera, and that this activity was lowest in the period of immature grapes, but highest during ripening. The highest polyphenol oxidase activity was obtained from the variety "Alfons" during ripening. There was a parallel relation between the amount of protein and polyphenol oxidase activity in all the varieties studied.