Pea protein isolates adsorption on phospholipid bilayer interfaces: a quartz crystal microbalance and neutron reflectometry study

Legumin and vicilin, the main storage proteins from peas, are increasingly employed as functional ingredients for food. The purpose of this work was to better understand the interactions between these proteins and selected lipids, due to their potential consequences on interfacial functionality of protein preparations. Legumin and vicilin isolates were obtained after isoelectric precipitation followed by further purification using size exclusion chromatography. The interactions were studied using DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine): DOPE (1,2-dioleoyl-sn-glycero-3 phosphoethanolamine) as mixed supported lipid bilayers, using quartz crystal microbalance with dissipation monitoring (QCM-D) and complementary neutron reflectometry (NR) experiments. This approach, fundamental in nature, allowed to observe interactions at the molecular level in the presence of phospholipids interfaces. QCM-D data suggested that legumin did not show any significant affinity for the investigated lipid interface. On the contrary there were changes in the bilayer with vicilin injection. NR experiments also supported these observations, and modeling of the experimental data also suggested a structural reorganization of the bilayer after vicilin injection and rinsing. This unique fundamental study of legumin and vicilin leads to the hypothesis that vicilin forms complexes with phospholipids bilayers which can be dispersed and removed by rinsing. All together, this study adds to the current debate on the importance of endogenous and non-endogenous phospholipids presence in affecting surface functionality of pea protein isolates. • Legumin and vicilin were further purified from pea protein isolate. • Their affinity bilayers composed of DOPC and DOPC: DOPE (80:20 v/v) were investigated. • Legumin did not interact with the phospholipid bilayer. • Vicilin showed adsorption, and structural rearrangements. • Modeling of neutron reflectometry data suggested the formation of complexes of vicilin with phospholipids.