NEW ANTHOCYANIN PIGMENTS FORMED AFTER CONDENSATION WITH FLAVANOLS

The formation of three major pigments has been detected in model solut ions imitating wine containing malvidin 3-monoglucoside (Mv-3-glu) and procyanidin B2 in the presence of acetaldehyde. Two of them were redd ish-blue compounds whose visible spectra are bathochromically shifted with regard to that of Mv-3-glu. They were assigned to two enantiomers containing Mv-3-glu and B2 moieties linked across their C-8 by an eth yl bridge. A molecular ion at mit 1097, consistent with such a structu re, has been established by LC/MS for both of them. The third majority pigment was an orange-red product possessing a spectrum with a maximu m wavelength in the visible region at 511 nm and a molecular ion at mi t 1093. A possible structure containing two flavylium mesomeric forms, corresponding to malvidin and to pelargonidin, has been suggested for this compound. This pigment proved to be more stable than the first t wo, as well as more resistant to discoloration by increased pH values and SO2. Similar pigments, whose spectra possess maximum wavelengths i n the visible region between 490 and 511 nm, have also been found in e quivalent solutions containing other flavan-3-ols [(+)-catechin, (-)-1 picatechin, or procyanidin B3]. Evidence for the formation in red win e of pigments with similar spectral characteristics is also contribute d.