Bioaccessibility and Antioxidant capacity of Epigallocatechin Gallate interacted with mung bean protein: Impact of protein structure

Abstract

The integration of plant proteins with bioactive compounds offers a promising strategy to enhance their environmental stability. This study explored the complexation of mung bean protein (MBP) with epigallocatechin gallate (EGCG) and the impact of affinity differences, arising from the structural variations of MBP, on the performances of the resulting complexes. MBP fractions obtained via ammonium sulfate precipitation displayed distinct protein compositions，especially MBP-60%S was mainly 8S vicilin. MBPs and EGCG rely on hydrogen bonding and hydrophobic interactions for spontaneous self-assembly, with hydrogen bonding dominating in higher soluble MBP. EGCG binding induced structural changes in MBPs, including an increase in α-helix content and size, alongside a reduction in β-sheet content and solubility. Notably, MBP-60%S exhibited the strongest affinity for EGCG. These conformational shifts enhanced EGCG’s thermal stability, mitigating the loss of antioxidant capacity due to EGCG’s thermal degradation. Moreover, the bioaccessibility of EGCG was increased by 1.91–3.22-fold. However, MBP-60%SE showed resistance to gastric digestion, likely due to altered protein structure and interaction strength. Overall, these findings provide valuable insights into the functionalization of plant proteins, offering a foundation for the development of high-quality functional foods and novel applications of mung bean protein.