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ABSTRACT Complex formation of anthocyanins with other plant constituents and the resulting color intensification enhances the possibility of their use as naturally occurring food colorants. Anthocyanins representing the four pigment groups characteristic for Vitis species, e.g. malvidin‐3‐glucoside, malvidin‐3‐p‐coumarylglucoside, malvidin‐3,5‐diglucoside and malvidin‐3‐p‐coumarylglucoside‐5‐glucoside in the concentration range 4 X 10 ‐6 to 4 X 10 ‐3 M were investigated for complex formation in the presence of the flavonol glycoside rutin (0‐2.4 X 10 ‐2 M). The experiments performed under conditions similar to those existing in grape juice showed a maximum color intensification of 1000% with malvidin‐3,5‐diglucoside. A 44 nm shift in the absorption maximum was observed concurrently with color intensification. The ability of the investigated anthocyanins to form deeply colored complexes with rutin decreased in the following order: malvidin‐3,5‐diglucoside (1000%), malvidin‐3‐p‐coumarylglucosid‐5‐glucoside (500%), malvidin‐3‐p‐coumarylglucoside (490%) and malvidin‐3‐glucoside (145%).
SCHEFFELDT et al. (Wed,) studied this question.