Comparative Analysis of the Effects of Different Organic Acids on Copigmentation and Stability of Anthocyanins in Purple Cabbage
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Abstract:
The present research was aimed at studying the copigmentation effect of organic acid on purple cabbage anthocyanin in water system. The results showed that with the increasing concentration of tartaric acid, erucic acid, ferulic acid, tannic acid and caffeic acid, the absorbance and preservation rates of the purple cabbage anthocyanins were increased, the maximum absorption wavelength red-shifted, and the browning index was decreased, indicating that organic acid had copigmentation effect for anthocyanin and the effect improved with the increasing concentration of organic acid; At 70, 80 and 90 ℃, organic acid copigmentated anthocyanins were in line with the first-order degradation kinetic model, and activation energy Ea was improved. Ea of tartaric acid group was increased by 67.70%, and t1/2 was 42.52, 36.87 and 13.15 h, respectively, which were significantly higher than those of the control group (9.47, 8.25 and 6.48 h, respectively). The thermal stability of anthocyanins was significantly improved (p<0.05). The Gibbs free energy ΔG and enthalpy change ΔH of the five organic acid auxiliary colors were positive, and the entropy ΔS was negative, indicating that the copigmentation was an endothermic nonspontaneous process with decreased variance. After anthocyanin copigmentation, L* showed an upward trend with the increase of temperature and the extension of time, while A * decreased, and tartaric acid group was significantly higher than the control group (p<0.05). The purple cabbage anthocyanins did not change before and after the copigmentation treatment, and it is speculated that the secondary color reaction was non-covalent bonding. It is concluded that organic acids have copigmentation effect on anthocyanin of purple cabbage, and it can be considered as cochromic agent to improve the stability of anthocyanin in food processing.
