ESTIMATION OF THE OXIDATIVE CHANGES IN PHENOLIC-COMPOUNDS OF CARIGNANE DURING WINEMAKING

The concentration of phenolic compounds during fermentation of Carigna ne musts exposed to air or protected from oxidation during pumping ove r operations was monitored by HPLC in order to evaluate the influence of oxidation in red wine making. All phenolic compounds accumulated du ring the first 3 to 8 days of maceration, due to extraction from the s olid parts of the grapes. At this stage, yeasts consumed all the avail able oxygen so that phenolic compounds were protected from oxidation. When the yeast activity decreased, enzymatic oxidation of polyphenolox idase substrates (caffeoyltartrate and p-coumaroyltartrate) and couple d oxidation of o-diphenols by the enzymically generated caffeoyltartra te quinones took place, resulting in approximately 20% losses of these compounds in the air exposed sample.