Heat-induced and concentration-dependent interactions between β-conglycinin and chlorogenic acid: Implications for protein stability, chlorogenic acid bioaccessibility, and antioxidant capacity

In this study, the effects of heat-induced and concentration-dependent interactions between β-conglycinin (7S) and chlorogenic acid (CQA) on the protein stability, CQA bioaccessibility, and antioxidant capacity was investigated. The results revealed that the effects of CQA on the structure of 7S are influenced by both concentration and temperature. Low concentrations of CQA minimally impacted the protein structure. However, at high concentrations, CQA could protect the secondary structure of 7S by forming hydrogen bonds and van der Waals forces instead of covalent bonding. Nevertheless, this weakened the structural stability between proteins, resulting in an accelerated denaturation process following heat treatment. Specifically, heat treatment at 65 °C and 121 °C reduced the binding affinity of these complexes by 99.20% and 97.24%, respectively, while the bioaccessibility of CQA decreased by 20.24% and 15.48% at 25 °C and 65 °C due to interaction with 7S; it remained unaffected at 121 °C. Although high CQA concentrations and heat treatment adversely affected the DPPH radical scavenging capacity, they had no significant impact on the ABTS scavenging capacity. Additionally, the low in vitro release rate of the CQA-7S complex suggested that it may have enhanced stability in the human gastrointestinal tract, potentially making it available to the microbiota. These findings underscore the importance of optimizing processing conditions to maximize the functional benefits of CQA and highlight the potential of soybean 7S protein as a delivery carrier for active substances that are sensitive to the gastrointestinal environment. • Heat treatment and the addition of CQA (1:100) changed the secondary structure of 7S. • 7S-CQA complexes by covalent bond were not formed at higher temperatures (121 °C). • Addition of high concentrations of CQA exacerbated 7S aggregation. • Non-covalent interaction between 7S-CQA promoted the antagonism of antioxidant capacity of complexes. • The addition of 7S decreased CQA in vitro bioaccessibility after heat treatment.