A Comparison of Anthocyanins and Wine Color Quality in Black Grapes of 39 Clones of Vitis rotundifolia Michx.

Abstract

Levels of 5 anthocyanins (Acy) in black muscadine grapes sampled in 1971 were compared with the visual color ratings and tristimulus values [“Theta” (hue), “L” (lightness), and “Sat” (saturation or chromaticity)] (Hunter Color and Color Difference Meter) of the wines made from grapes of these same clones (vines) in 1968 and aged in the bottle for 1 year. Neither total Acy content, which varied 50-fold, nor contents of the diglucoside (diglc) of delphinidin (Dp), present in larger quantities than those of the other 4 Acy, was associated with a good wine color. In all instances, good red wine color was associated with the presence of 8 or more mg of malvidin-3,5-diglc/100-g of fresh grapes. Good color of wines was also associated with low “Theta” and “L” tristimulus values. These 2 values were well correlated with each other. Multiple correlations indicated that 62% of the variation in “Theta” was accounted for by the natural logarithm of contents of diglc of malvidin (Mv), petunidin (Pt) and cyanidin (Cy) in the grapes. However, 42% was explained by the regression of Mv-3,5-diglc alone. Malvidin-3,5-diglucosides thus had the greatest effect on the hue of the wine. Over 75% of the variation in the tristimulus “L” value of the wine was accounted for by the regression of Pt-3,5-diglc with it. Therefore, good red wine color was largely dependent upon high levels of Mv and Pt diglc in fresh grapes.