The competition between endogenous phospholipids and proteins from pea protein isolate rules their interfacial properties

Sustainable incentives foster the use of plant-based ingredients as emulsifiers, but their composition, functionality and interfacial properties deserve more attention. A recent study highlighted high contents of endogenous phospholipids in pea protein isolate (PPI) and the potential of high-pressure homogenization (HPH) to release submicron lipid structures in aqueous suspensions. These findings raised the pivotal question of the interfacial properties of this widespread ingredient, suggesting a competition between proteins and phospholipids for interfacial adsorption. Dilatational interfacial rheology measurements were conducted using either the soluble fraction of the ingredient as such, lipids extracted from PPI, or purified pea proteins (7S). Oscillatory deformations of the oil-water interfacial layers were analyzed using Lissajous plots, which substantiated the interactions between proteins and lipids by deciphering their respective contributions. The formation of mixed interfacial films according to the protein-to-lipid ratio was demonstrated, with a prevalent influence of pea lipids on the rheological signature of the films. Atomic force microscopy confirmed the formation of mixed interfacial films where lipid domains coexist with protein aggregates. These insights advance the current knowledge regarding the complexity and functionality of plant protein ingredients, which is important to promote the rational formulation of plant-based food products.