Caffeic acid copigmentation of anthocyanins from Cabernet Sauvignon grape extracts in model systems

Caffeic copigmentation of anthocyanins from Cabernet Sauvignon grape extracts in model system and yoghurt model system was investigated, as well as the influence of copigmentation on the stability of these pigments. In the model system, the dependence of anthocyanin stability on added caffeic acid was evaluated at temperatures (4 ± 1 °C and 29 ± 3 °C) and in the presence or absence of light, at two pH values: 3.0 and 4.0; in the yoghurt model system, the stability of the anthocyanins was evaluated at 4 ± 1 °C in the dark. The half-life and percentage of color retention of the anthocyanins in all treatments was calculated. The spectrophotometric results (Δλ, ΔA) revealed that interaction occurred between the crude extract of anthocyanins and caffeic acid suggesting copigmentation. The addition of caffeic acid (1:1 w/v) significantly increased (p < 0.05) the stability of anthocyanins in both model and yoghurt systems. In the model system the temperature and presence of light significantly influenced the stability of anthocyanins (p < 0.05), where the highest values for half-life were obtained for anthocyanins with caffeic acid at pH 3.0, stored in the dark at a temperature of 4 ± 1 °C (6.930 h). In the yoghurt system the caffeic acid increased the half-life time of anthocyanins to 6673 h.