Molecular interactions by thermodynamic and computational molecular docking simulations of selected strawberry esters and pea protein isolate in an aqueous model system

Abstract

The objective of this study was to determine the interactions between selected strawberry esters and pea protein isolate (PPI) in a protein-containing aqueous model system, utilizing modified ultrafiltration and equilibrium dialysis techniques. Strawberry esters, including ethyl butanoate, ethyl isopentanoate, ethyl hexanoate, and methyl anthranilate, demonstrated different binding parameters to the PPI. Overall flavor binding affinities (nK) of all esters decreased as the temperature increased from 5 °C to 25 °C. Among these compounds, ethyl hexanoate exhibited the highest affinity to PPI at 25 °C. Thermodynamic parameters revealed that all ester-PPI interactions were spontaneous and enthalpy-driven, primarily involving van der Waals forces or hydrogen bonding. In addition, computational molecular docking studies also identified alkyl hydrophobic interactions in ester-PPI complexes. These findings illustrated that understanding the interactions between esters and PPIs can assist in determining the optimal proportions of compounds for flavorings in high-protein beverages from pea protein.