Products formed in model wine solutions involving anthocyanins, procyanidin B-2, and acetaldehyde

Interaction between anthocyanins (3-glucosides of cyanidin, peonidin and malvidin), procyanidin B-2 (B-2), and acetaldehyde and the formation of new colored compounds was studied in model wine solutions. The anthocyanin-procyanidin B-2 condensation reaction showed first-order kinetics with or without the presence of acetaldehyde, and the reaction rates were calculated, In all the model solutions containing anthocyanins, procyanidin B-2, and acetaldehyde, rapid color augmentation with shifts toward violet-were observed. Two principal new compounds (thought to be trimers, Linked at different positions) were detectable by HPLC, and their spectral properties were studied by diode-array spectroscopy. Malvidin 3-glucoside reacts more slowly than. cyanidin 3-glucoside and peonidin-3 glucoside. Similar color changes were observed in model solutions containing anthocyanins alone with acetaldehyde. Finally, we observed that the degradation constant rates for each anthocyanin increased in the following order: anthocyanins alone < anthocyanins + B-2 < anthocyanins + acetaldehyde < anthocyanins + B-2 + acetaldehyde. Similar increasing order of the reaction rates of procyanidin B-2 was observed. In both cases, the presence of acetaldehyde was of major importance in accelerating the chemical transformation of phenolic compounds, inducing the formation of new products.