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Effect of Microoxygenationon Colorand Anthocyanin-Related Compoundsof Wines withDifferent PhenolicContentsCano-López, M.; Pardo-Mínguez, F.; Schmauch,G.; Saucier, C.; Teissedre, P.L.; López-Roca, J.M.; andGómez-Plaza, E.Departamento de Tecnología de Alimentos, Nutricióny Bromatología, Facultad de Veterinaria, Universidadde Murcia, Spain, Bodegas San Isidro, Jumilla, Murcia,Spain, and Faculté d’Oenologie, Université VictorSegalen, Bordeaux 2, FranceSeveral factors may affect the results obtained whenmicro-oxygenation is applied to red wines, the mostimportant being the moment of application, the dosesof oxygen, and the wine phenolic characteristics.In this study, three red wines, made from Vitis viniferavar. Monastrell (2005 vintage) and with different phenoliccharacteristics, were micro-oxygenated to determineas to how this technique affected the formationof new pigments in the wines and their chromaticcharacteristics. The results indicated that the differentwines were differently affected by micro-oxygenation.In general, the micro-oxygenated wines had a higherpercentage of new anthocyanin-derived pigments,being that this formation is more favored in the wineswith the highest total phenol content. These compounds,in turn, significantly increased the wine colorintensity. The wine with the lowest phenolic contentwas less influenced by micro-oxygenation, and theobserved evolution in the degree of polymerizationof tannins suggested that it might have suffered overoxygenation.KEYWORDS: Wine; color; anthocyanins; anthocyanin-derivedcompounds; micro-oxygenation.INTRODUCTIONPhenolic compounds are responsible for many of theorganoleptic characteristics of wines. Among them,anthocyanins are responsible for the color of red wine,Seminario TécnicoCompuestos azufrados volátiles en vinoswhile their interactions with other compounds largelydetermine the color changes observed in maturingwines. The wine phenolic content depends on thegrape characteristics and on the winemaking process.Factors such as phenolic maturity of the grapes, lengthof maceration, frequency of pumping over, etc. determinethe final wine phenolic content (1–3).The importance of oxygen in the evolution of winecolor has been studied for many years, both as regardsits role in polyphenol oxidation (4–7) and as a promoterof the formation on new anthocyanin-derivedcompounds (5, 8–11). Indeed, one way of manipulatingthe phenolic structure of a wine is to use themicro-oxygenation (MO) technique, which relies onthe formation of microbubbles through the injectionof gaseous oxygen into the wine using a microdiffuser(12). These bubbles rise through the wine, dissolvingas they travel to the surface.Empirical results have indicated that MO benefits includethe stabilization of wine color, the softening oftannins, and the lessening of vegetative aromas (13,14). Reactions involving wine polyphenols are the keyto these processes, which include changes in proanthocyaninchain length and the consequent effect onwine astringency and the linking of anthocyanins andtannins to form more stably colored forms. Dissolvedoxygen leads to the formation of acetaldehyde that, inturn, reacts with flavanols and anthocyanins to inducethe formation of a very reactive carbocation that quicklyreacts with another flavanol molecule or with anthocyanin,producing ethyl bridge-linked compounds(15, 16). They are unstable (17) and undergo reactionsthat lead to the formation of new compounds suchas flavanyl pyranoanthocyanins. These end productsare more stable and colored than the original compounds(11). Moreover, incorporation of anthocyanininto tannin structures also may lead to a decrease inastringency (18).Since its commercial adoption, MO has become commonpractice and is now used worldwide, althoughmost of the available information is from empirical results.Only a few scientific publications can be foundthat are related to the effects of MO (8, 19–23). Severalfactors may affect the final results obtained by MO,the most important being the moment of application,doses of oxygen, and wine characteristics. Wines havemarked differences in their respective abilities to consumeoxygen. As a general rule, this facility is directlyrelated to their relative concentration of polyphenolssince phenolic compounds are the main consumersof oxygen (60%) together with ethanol (20%) and SO 2(12%) (22). In our first studies, we tested the use of differentdoses of oxygen and the effect of the momentof application on wine chromatic characteristics (23,24). Here, we report the results of a commercial scaleMO experiment where the influence of applying oxygento three wines made from Monastrell grapes ofJ. Agric. Food Chem. 2008, 56, 5932–5941Textos asociados91