Reaction between malvidin 3-glucoside and (+)-catechin in model solutions containing different aldehydes

The contribution of the aldehyde composition of wine spirit to the color changes in Port red wine was studied in model solutions. Malvidin 3-glucoside was shown to be very reactive towards catechin in the presence of different aldehydes: acetaldehyde, isovaleraldehyde, benzaldehyde, propionaldehyde, isobutyraldehyde, formaldehyde, and 2-methylbutyraldehyde. LC/MS data confirmed the formation of oligomeric pigments resulting from the reaction between the anthocyanin and the flavanol (colored products) and between 2 flavanol units (colorless products) mediated by each aldehyde assayed. The W-visible spectra of the colored pigments showed a lambda(max) bathochromically shifted relatively to the lambda(max) of original anthocyanins. All samples revealed a "blueing" and "darkening" color effects using the CIELAB system.