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Wine phenolic composition depends on the grapes used to make the wine and on the vinification conditions and a wide range of variables such as cultivar, viticulture practices and vinification techniques can affect the phenolic composition of red wines. Changes in polyphenol content and antioxidant activity during storage over 6 months in bottles were studied in Monastrell varietal red wines from grapes obtained by organic and conventional agricultural practices. Also it was studied the relationship between antioxidant activity and phenolic compounds. The results showed that the contents of anthocyanins decreased during storage although hydroxycinnamics derivatives, stilbenes and flavonols do not suffer significative changes. The total antioxidant activity of conventional and organic wines was well correlated especially with anthocyanins at first month of storage and flavonols all time. Stilbenes had a high correlation with antioxidant activity in both types of wine especially in the last month of storage (r 2 = 0.74), and hydroxycinnamic derivatives had a poor correlation with antioxidant activity. Evolution of phenolics compounds and antioxidant activity in conventional and organic wines were similar during storage. Not significant differences were observed in conventional and organic wines.

Co-winemaked Monastrell wines with Cabernet Sauvignon or Merlot, at different proportions have been studied for first time in terms of its odor activity value (OAV) in young wines, aging wines (after 9 months in French oak barrels) and bottled aging wines (aging wines after 6 months in the bottle). The co-winemaking wines showed a different aromatic complexity as they were fruitier and sweeter than the monovarietal ones, enhancing their aroma characteristics, being more evident at 60:40 proportion in case of Merlot for young and aging wines and Cabernet Sauvignon for bottled ones. In terms of extractable oak compounds, Monastrell–Merlot wines showed the highest values suggesting that they may need a shorter period within the barrel than Monastrell–Cabernet Sauvignon ones.

Micro-oxygenation (MOX) was applied to a red wine for 5 months following the end of alcoholic fermentation and then both a non-oxygenated control wine and the micro-oxygenated wine were matured in oak barrels or bottles. The concentration of anthocyanin and anthocyanin-derived compounds and the chromatic characteristics of the control and micro-oxygenated wines after the maturation period were studied. Anthocyanin and anthocyanin-derived compounds composition were determined by liquid chromatography-mass spectrometry; and, together with monomeric anthocyanins, compounds including direct anthocyanin-flavanol adducts, ethyl-linked anthocyanin-flavanol compounds, and pyranoanthocyanins were identified. The results showed that the improvements in the chromatic characteristics obtained by applying the MOX technique to Monastrell wines were maintained after an aging period in bottle or barrel. The color intensity of wines increased during maturation in oak barrels, whereas the color of the bottled wines decreased, although MOX wines always showed higher color intensity than the respective control wines. Bottled wines also showed a higher increase in tint and a lower quantity of compounds resistant to SO2 discoloration than oak matured wines, indicating that the formation of these compounds is favored by the oxidative conditions in oak barrels.