Atmospheric cold plasma modification of pea protein isolate enhances the structure, stability, and functionality of plant-based bigels.

This study investigated the effect of atmospheric cold plasma treatment on the physicochemical properties of pea protein isolate (PPI) and its application in the development of plant-based bigel systems composed of transglutaminase-induced PPI hydrogels and glycerol monostearate-structured sunflower oil oleogels. Plasma treatment reduced particle size, modified the surface charge, surface hydrophobicity, interfacial activity, and secondary structure of PPI, without substantial changes in the molecular weight distribution of the major protein fractions. Bigels prepared using plasma-treated PPI exhibited stable biphasic structures with high oil-binding capacity (OBC) and water-holding capacity (WHC), and plasma-treated formulations generally showed slightly higher liquid retention than their untreated counterparts during refrigerated storage. Quantitative fluorescence microscopy revealed smaller dispersed domains following plasma treatment, indicating a finer phase distribution within the biphasic matrix. Rheological measurements demonstrated predominantly elastic behavior (G' > G″) for all samples, while plasma-treated bigels showed higher viscoelasticity and greater resistance to deformation. Texture profile analysis further revealed increased hardness, cohesiveness, gumminess, and chewiness, indicating the formation of stronger and more integrated gel networks. Fourier-transform infrared spectroscopy suggested that hydrogen bonding and other noncovalent interactions contributed to bigel stabilization without forming new chemical bonds. Thermal analysis showed enhanced thermal stability and more controlled degradation behavior in plasma-treated systems. Overall, formulation composition and H:O ratio were the major factors governing bigel properties, while atmospheric cold plasma treatment further modified the colloidal and structural characteristics of PPI and influenced the organization of the resulting biphasic systems, demonstrating its potential as a non-thermal protein-modification approach for structured food applications.