DETECTION OF COMPOUNDS FORMED THROUGH THE REACTION OF MALVIDIN 3-MONOGLUCOSIDE AND CATECHIN IN THE PRESENCE OF ACETALDEHYDE

The interaction between catechin and malvidin 3-monoglucoside in the p resence of acetaldehyde was studied in model solutions. The initial fo rmation of two pigments (I and II), which later evolved to more conden sed structures, was observed. Evidence was found that for these pigmen ts to be formed, catechin should first react with acetaldehyde and the resulting adduct later condenses with anthocyanin; it is proposed tha t pigments I and II are two enantiomeric structures of the catechin(8- ->)-acetyl-(-->8)-anthocyanin dimer. For their formation, a relatively acidic pH is necessary; this is attributed to the demand that the ace taldehyde should be in cationic form for condensation to occur. Conden sation among catechin units involving acetaldehyde was also seen. Mino r amounts of substances from the degradation of anthocyanin were detec ted, indicating that in the presence of acetaldehyde it is basically c ondensation and not degradation of the anthocyanin that occurs.