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

Abstract

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