Formation of anthocyanin-derived pigments in experimental red wines

Red wines obtained by microvinification in the laboratory and adjusted to three pH values (3.2, 3.6 and 4.0) were examined for the formation of anthocyanin-derived pigments throughout nine months of storage in bottles at 15 degrees C. The formation of the pigments was also followed in aliquots of the wines at pH 3.2 with added acetaldehyde (800 mg/L). Pigment analyses were accomplished by HPLC using double on-line detection by diode array spectrophotometry and mass spectrometry. Two different types of pigments were observed. The first were products derived from the condensation between anthocyanins and flavanols by ethyl bridges. The second corresponded to products showing an additional heterocycle in the anthocyanin structure (vitisin-like pigments); of these, vitisin B, which derives from malvidin 3-monoglucoside, was the most important one. Products similar to vitisin B derived from other anthocyanins were also detected, as well as structurally related pigments containing flavanol moieties. The formation of all these pigments involves the acetaldehyde, since they appeared or were enhanced as a result of its addition, and were also favored in more acidic wines.