Copigmentation effects of phenolics on color enhancement and stability of blackberry wine residue anthocyanins: Chromaticity, kinetics and structural simulation

To expound the copigmentation effects of phenolics on blackberry wine residue anthocyanins (BWRA), the color and stability of BWRA with storage, thermal, light and oxidation treatments were evaluated by chromaticity, kinetics and structural simulation analysis. Results indicated that phenolic acids showed preferable copigmetation on BWRA solutions with the enhanced color, thermostability at 50-70 degrees C and light stability, whereas the degradation was accelerated at 90 degrees C. Meanwhile, flavonoids promoted the oxidation stability of BWRA. Of all the phenolic acids, ferulic acid presented the best copigmentation effect, and among the flavonoids rutin was the most active. Structural simulation suggested rutin and ferulic acid had the largest volume, potential energy (164.8 and 32.8 kcal/mol), minimized energy (39.2 and 11.3 kal/mol) and van der Waals energy (81.6 and 28.1 kcal/mol), respectively, which were favorable to the stabilization of the flavylium ion. The hydrogen bonding, pi-pi stacking and solvent effects were together involved in the copigmentation mechanism.