Soy lecithin strengthens amaranth protein-based omelettes through protein complexation which alters protein interactions

Abstract

A plant-based omelette with comparable texture and protein content could more effectively address egg shortages. To strengthen the plant-based omelette prepared by frying an amaranth-protein-stabilised emulsion, with protein (11.6 %) and lipid (9.74 %) contents similar to eggs, the effect of adding soy lecithin (0.50–2.00 % w/w) to the emulsion was investigated. This approach was promising given the structural and conformational changes reportedly induced by soy lecithin upon complexation with various plant proteins. Confocal imaging and the binding energy of soy phosphatidylcholine to 11S globulin (-6.01 kcal/mol) indicated complexation between lecithin phospholipids and the proteins. This complexation exposed amino acids, including tryptophan and tyrosine, from the hydrophobic core, thereby promoting hydrogen bonding involving 7S globulin, 11S globulin, and albumin. Consequently, intermolecular β-sheet content rose from 21.5 % to 25.5 % with increasing lecithin content in the plant-based omelette. Enhanced aggregation of 11S globulin and albumin, along with lecithin-induced sulfhydryl group exposure, promoted disulfide bond formation (25.8–30.9 %) upon heating. These interactions improved protein network connectivity under SEM, such that increasing lecithin content strengthened the plant-based omelette. The plant-based omelette containing 1.0 % lecithin had the closest texture to the egg omelette, with distinguishing parameters including dynamic consistency index (94.1 vs. 95.6 kPa·s^n*) and maximum creep compliance (6.12 vs. 5.98 [×10⁻⁶ Pa⁻¹]) for viscoelastic properties, along with ultimate tensile strength (22.1 vs. 21.9 kPa). As a healthy option with a similar texture, this plant-based omelette could appeal to consumers seeking sustainable, animal-friendly egg alternatives. This study demonstrated the potential of lecithin in texturing plant protein-based foods.