Polyphenols, colour and antioxidant activity changes in in four Italian red wines during storage

The evolution, during one year of storage, of the antioxidant activity, phenolic compounds and colour of four red wines, obtained from two different Sardinian important cultivars (Cannonau and Cagnulari) and kept in stainless steel tanks or in bottle, was evaluated. Two samples were subjected to the microoxygenation process, with one of these derived from a late grape harvest. Wines stored in stainless steel tanks showed a decrease in phenolic content and antioxidant activity, while the bottled wine did not show significant variations. The different degree of microoxygenation caused some significant differences with regard to the decrease in phenolic compounds during the storage, being lower in the sample microoxygenated for a longer time and with more oxygen. Correlation coefficients between anthocyanins and antioxidant activity were high for all the samples analysed. Regarding the colour, percent of blue showed a significant increase in microoxygenated wines. PCA, applied to the data set of phenolic compounds showed that Cannonau wine is different from Cagnulari samples, because of the higher content of cinnamic acids. Cagnulari bottled wine differed from the two Cagnulari stored in steel tanks, in particular for the anthocyanins content, confirming the reducing activity of the bottle