| Abstract
| - The copigmentation effect of prefermentation additions of different doses of caffeic acid wasinvestigated during the 1997 harvest. Microfermentation with the major red grape cultivars Listánnegro and Negramoll, grown in the Canary Islands, was carried out with the same protocol. Visibleand UV spectra were registered periodically. HPLC chromatograms were carried out. The colorenhancement of cv. Negramoll wine varied between 13 and 75% (AU at 520 nm), and that of cv.Listán negro wine between 25 and 45% at the end of fermentation. During aging these values wereenhanced to reach even >100% in some cases. An initial complex of the 1:1 type, where one moleculeof caffeic acid associates with one molecule of anthocyanin, has been identified using the mathematicalprocedure of Brouillard et al. (J. Am. Chem. Soc.1989, 111, 2604−2610). Caffeic acid seems tocontribute to color stability and protection against oxidation. The importance of nonpigment compositionin pigment extraction and color retention during and after fermentation is demonstrated. Keywords: Copigmentation; caffeic acid; red wine; UV−visible spectrophotometer; color wine
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