Effect of the Structure of Seven Anthocyanins on Self-association and Colour in an Aqueous Alcohol Solution

Anthocyanins play an important role in the colour of red wine or mulberry wine. The effect of anthocyaninstructures (substitution therein) on the self-association and colour in an aqueous alcohol solution wasinvestigated in order to provide helpful knowledge about the relationship between anthocyanin structureand colour. The addition of hydroxyl at the C3' position weakens self-association, whereas addition at theC5' position facilitates self-association. However, the hydroxyl substitutions at the C3' and C5' positionsenhance colour. The methoxy substitutions at the C3' and C5' positions enhance the self-association and thecolour. The replacement of glucoside with the disaccharide rutinoside at the C3 position was detrimentalto self-association, but the substitution of rutinoside at the C3 position produced a stronger colour thanthe substitution of glucoside at the same position. Cyanidin 3-O-glucoside and cyanidin 3-O-rutinosideenhanced colour via intramolecular co-pigmentation instead of self-association. The anthocyanin colourwas affected synthetically by the types and positions of the substituent in the anthocyanin molecule