Study of the reactions between (+)-catechin and furfural derivatives in the presence or absence of anthocyanins and their implication in food color change

((+)-Catechin was separately incubated with furfural or with 5-(hydroxymeth yl)furfural, and the formation of new oligomeric bridged compounds having f lavanol units linked by furfuryl or 5-hydroxymethylfurfuryl groups was obse rved. LC/ESI-MS analyses detected four dimeric adducts along with intermedi ate adducts in each solution, and reaction was faster with furfural than wi th hydroxymethylfurfural. In addition, new compounds exhibiting the same W- visible spectra as xanthylium salts with absorption maxims around 440 nm we re also detected. When malvidin 3-O-glucoside or cyanidin 3-O-glucoside was added to the mixtures, new oligomeric colorless and colored pigments invol ving both (+)-catechin and anthocyanin moieties were detected, showing thus that the two polyphenols competed in the condensation process. Among the o btained colored pigment adducts, two dimeric compounds in which the flavano l was bridged to the anthocyanin were observed. Their UV-visible spectra we re similar to the spectrum of malvidin 3-O-glucoside, but their maximum in the visible region was bathochromically shifted.