9.00-10.00 Viernes 2 de Julio de 2010
a cargo del Dr. Roger Boulton, Department of Viticulture and Enology, University of California
Red wines present considerably darker and different color than would be expected from their pigment composition. The extent of anthocyanin copigmentation, which can account for between 30 and 50% of young wine color, is directly related to the presence of other colorless components found in the juice and skins of grapes. The concentrations and identity of these copigmentation cofactors varies widely between the cultivars and the conditions under which they have been grown. A non-linear multivariate model that relates the concentrations of major cofactors to the color due to copigmentation is presented. The changes in this aspect of color due to oxidation of cofactors, the depletion of bitartrate ions and the slow formation of polymeric pigment are reviewed. A simple model for the formation of polymeric pigment is presented. The role of the colorless cofactors and tannin, and winemaking practices which influence these, on the color displayed by young and aged red wines is described.
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