Ultrasound-assisted limited enzymolysis of cottonseed protein: Structural, rheological, and techno-functional attributes

This research investigated the ability of cavitation and/or limited enzymolysis (10–40 min) to modify the structural, rheological, physical, and functional properties of cottonseed protein (CP). Topographical images revealed that sonicated CP hydrolysates (CPH) exhibited more disrupted and disordered structures, with fragmented and partially destroyed particles, compared to their non-sonicated counterparts, implying that the combined treatment (i.e., sonication and enzymolysis) impaired the intermolecular interactive forces and cross-linking. UV-Vis absorption and intrinsic fluorescence spectroscopic analyses indicated that the combined approach, particularly with 30 min of enzymolysis, substantially augmented the molecular flexibility of the CP isolate. Furthermore, sonication-assisted enzymolysis markedly increased the exposure of sulfhydryl groups in CP, while simultaneously reducing disulfide bond content, viscoelasticity, viscosity, and turbidity relative to other treatments, demonstrating the breakdown of protein polymer chains. Interestingly, enzymolysis alone reduced the fat-binding capacity and foam stability (as evidenced by foam morphology) of the native protein (p < 0.05). In contrast, sonication-assisted enzymolysis enhanced (p < 0.05) the water-binding capacity, emulsifying characteristics, and foamability of CP over sonication or conventional enzymolysis alone. Finally, Pearson’s correlation analysis showed that the functional attributes of CP and CPH samples were strongly associated with their conformational characteristics. These outcomes provide a viable strategy for enhancing the rheological behavior and techno-functionality of CP for food applications.