Structural properties, rheological characteristics, and drug delivery efficiency of resveratrol-loaded soybean protein isolate and hemp protein isolate emulsion gels: Synergistic effects of carboxymethyl cellulose incorporation and ultrasound treatment

Plant protein emulsion gels often show suboptimal mechanical properties. This study aimed to improve the protein secondary structure, rheological behavior, and resveratrol (RES) delivery performance of soybean protein isolate (SPI)-hemp protein isolate (HPI) emulsion gels via carboxymethyl cellulose (CMC) incorporation combined with ultrasound treatment. Initially, the degree of protein-polysaccharide grafting increased with the rise in CMC concentrations before decreasing thereafter. The partial conversion of α-helices to β-sheets exposed hydrophobic groups, facilitating the formation of an interpenetrating protein-polysaccharide network. Rheological analysis revealed that CMC decreased the ellipticity of elastic Lissajous curves and inhibited the linearization of viscous Lissajous curves, thereby improving resistance to the external environment. Moderate ultrasound treatment (400 W) further enhanced the encapsulation efficiency (71.84%), loading capacity (23.46%), and bioaccessibility (40.31%) of RES within the gels. In contrast, excessive ultrasound treatment (800 W) weakened protein-CMC interactions. Overall, combined CMC-ultrasound treatment effectively improved the mechano-structural properties and bioactive compound delivery performance of plant protein emulsion gels.