The Role of Copigmentation with Phenolic Compounds on the Vitamin C Resistance and Antioxidant Activity of Anthocyanins

Coexistence of vitamin C is known to expedite the degradation of anthocyanin and leads to serious color deterioration. The aim of this study was to elucidate whether the copigmentation occurred between anthocyanin and phenolic compounds could improve the resistance of anthocyanin against vitamin C and improve its color stability. Two model systems (pH 2 and pH 3) with five varieties of phenolic compounds (ferulic acid, gallic acid, catechin, chlorogenic acid, and caffeic acid) were investigated. The effect of copigmentation on assorted characteristics such as color qualities (Degradation Index, halflife and retention percentage of the pigment), activation energy for degradation and antioxidant capacity were studied. In addition, bathochromic shift and hyperchromic effect were also examined to quantify the degree of copigmentation. The results showed that copigmentation between anthocyanin and phenolic compounds (especially chlorogenic acid at pH 3) would significantly increase the anthocyanin stability against vitamin C, heat and sulfide, which also ledto an enhanced antioxidant capacity. Further analysis revealed that FRAP increased with increased molar ratio of added polyphenols as well as the degree of bathochromic shift, and the increase of antioxidant capacity mainly came from polyphenols. HPLC analysis confirmed the existence of a novel substance of copigment complex. In conclusion, the copigmentation may significantly decrease the anthocyanin degradation caused by vitamin C, and increase the antioxidant capacity of the system.