Interactions of pea protein with three sulfur-containing flavor compounds: Insights into molecule structural, non-covalent, and binding mechanisms

Understanding the interaction mechanisms between flavor active compounds and protein matrices is pivotal for advancing the texture and mouthfeel of high-quality meat analogs, for plant-based food development. This study provides the first systematic investigation of the interaction mechanisms of sulfur-containing flavor compounds (SCFCs) with pea protein isolate (PPI) through multispectral spectroscopy and molecular docking. We focus on three structurally distinct SCFCs: dimethyl disulfide (DMD, linear), dimethyl trisulfide (DMT, linear), and lenthionine (LEN, cyclic). Results showed that within 0–0.5 mM, SCFC concentration positively correlated with the flavor retention rate of PPI. The molecular structure and hydrophobicity of SCFCs significantly influenced the binding affinity of flavors to PPI, with the binding strength ordered as LEN > DMT > DMD. Multispectral analyses and AFM imaging revealed that after combination with flavors, the PPI spatial structure changed significantly from a highly ordered rigid structure to a relatively flexible disordered feature. The E-nose analysis, coupled with correlation analysis, revealed that the addition of SCFCs altered the odor characteristics of PPI, amplifying meat-like sulfur aroma and diminishing bean-associated alcohol and aldehyde odors. Thermodynamic assessments, bond-breaking experiments, and molecular docking further validated the dominance of non-covalent forces and structural specificity dictated binding strength: LEN (cyclic) exhibited the highest affinity via hydrophobic interactions. At the same time, DMT (linear) relied on hydrogen bonding. These findings establish a structure-driven framework for optimizing flavor retention in PPI-based meat analogs, addressing a theoretical foundation for flavor control in plant-based food development.