Entrapment of cyanidin-3-O-glucoside in β-conglycinin: From interaction to bioaccessibility and antioxidant activity under thermal treatment

•Thermal treatment and the addition of C3G (1:100) changed the secondary structure of 7S.•No 7S-C3G covalent complexes were formed after thermal treatment at 25–121 °C.•Non-covalent interaction between 7S-C3G decreased the antioxidant capacity of complexes.•The 7S addition decreased C3G bioaccessibility after thermal treatment.•Stronger affinity of C3G-7S promoted the antagonism of antioxidant capacity between 7S and C3G. The thermal-induced interaction between β-conglycinin (7S) and cyanidin-3-O-glucoside (C3G) on the bioaccessibility and antioxidant capacity of C3G was investigated. High ratio of 7S to C3G (1:100) led to a more ordered secondary structure of 7S. Thermal treatment promoted the formation of 7S-C3G complexes via hydrophobic and hydrogen bonds but did not induce the formation of 7S-C3G covalent products. Thermal treatment at 65 °C and 121 °C enhanced the binding affinity of 7S-C3G complexes by 46.19 % and 1203 % compared with 25 °C. The 7S-C3G interaction decreased C3G bioaccessibility by 4.37 %, 8.74 %, and 46.37 % at 25 °C, 65 °C, and 121 °C. Diphenylpicrylhydrazyl (DPPH) and ABTS antioxidant capacity assay indicated an antagonistic effect between 7S and C3G. The increased binding affinity of C3G to 7S limited the bioaccessibility of C3G and promoted the antagonism of antioxidant capacity between 7S and C3G. 7S addition was detrimental to the antioxidant capacity and bioaccessibility of C3G in vitro after thermal processing.