Four new anthocyanin pigments were found in red wines in trace amounts and are thought to be formed in wines during maturation. Their structures were established by FAB-MS and NMR. Two pigments were identified as the 3-glucoside (vitisin A) and the 3-acetylglucoside (acetylvitisin A) of malvidin containing a C3H2O2 grouping, linking carbon 4 and the 5-hydroxyl group of its molecule (vitisidin A). The other two anthocyanins were identified as the 3-glucoside (vitisin B) and the 3-acetylglucoside (acetylvitisin B) of malvidin containing a CHCH moiety linking carbon 4 and the 5-hydroxyl group of its molecule (vitisidin B or decarboxyvitisidin A). Unlike other anthocyanins these novel compounds were found to be wholly or partly resistant to bleaching by sulfur dioxide and express more color up to pH 7 than malvidin 3-glucoside. Detailed spectral measurements from 250 to 770 nm up to pH 7, including the use of CIELAB 76 measurements, indicate the formation of stable quinonoidal bases, confirming that there could be little formation of the colorless carbinol base forms. Keywords: Red wine; anthocyanins; vitisin A; vitisin B; vitisidin A; vitisidin B; NMR; FABMS

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An isolation procedure was developed for the recovery of the cinnamate derivatives from Miiller-Thurgau white wine by means of adsorption on charcoal, elution with acidic methanol and repeated chromatography on Sephadex LH-20 with dilute acetic acid as the eluent. The crystalline products recovered were cis-and trans-p-coumaroyl-(+ )-tartaric (coutaric) acid and trans-caffeoyl-( +)-tartaric (caftaric) acid, as shown by spectral data, hydrolysis, chromatography, etc. The corresponding quinates were not detected and neither were ferulic acid derivatives nor the free cinnamic acids in this young white wine. The data are briefly discussed in relation to previous reports on these compounds in grapes or wines and their significance as wine constituents.

The distribution of anthocyanins in methanolic skin extracts of 16 grape cultivars used for port wine production and grown at five sites in the Douro Valley in Northern Portugal has been assessed by high performance liquid chromatography. Results are confined to the seven most readily separated and identified anthocyanins and are expressed as percentages of their total (88-99% of the total integrated area). Anthocyanins based on malvidin (Mv) predominated. Of these, Mv 3-glucoside was the major pigment (33-60%), being exceeded by Mv 3-p-coumarylglucoside (2-51 %) in only two cultivars; Mv 3-acetylglucoside (1-15%) was consistently the lowest. Peonidin 3-glucoside (1-27%) was prominent in four cultivars, but delphinidin 3-glucoside (1-11 %), petunidin 3-glucoside (2-1 1 %) and cyanidin 3-glucoside (traced%) were of low proportions throughout. The ratio Mv 3-acetylglucoside/total Mv glucosides appeared characteristic of cultivar, independent of site, and a useful aid to identification of grape cultivars. The coloured pulp of some cultivars contained peonidin 3-glucoside as a major component, present in greater proportions than in the skin; the percentage of Mv 3-p-coumarylglucoside was lower in pulp than in skin. The identities of six of the seven anthocyanins were confirmed by fast atom bombardment mass spectrometry and the structures of the Mv derivatives were determined by nuclear magnetic resonance. The formation of formyl and acetyl anthocyanin artefacts is described.