pH-shifted walnut protein-bamboo shoot soluble dietary fiber complexes for structuring glucono-δ-lactone-acidified...

This study developed high-oil (70% v/v) cold-set emulsion gels using pH-shifted walnut protein isolate (PWPI) and bamboo shoot soluble dietary fiber (SDF). pH-shifting significantly improved the solubility of walnut protein from 20.84% to 77.15% and promoted the formation of smaller, more stable protein particles. After SDF incorporation, the resulting PWPI-SDF complexes showed improved colloidal and interfacial properties for stabilizing oil-in-water emulsions. At 0.5% (w/v) SDF, the emulsions exhibited a more uniform droplet distribution and stronger viscoelastic behavior. GDL (Glucono-δ-lactone) was then used to induce cold-set gelation of the emulsions. Among the tested formulations, the gels prepared with 1.5% GDL showed higher β-sheet content, enhanced hydrogen-bonding interactions, improved elasticity, and better textural properties. LF-NMR and MRI further indicated greater water immobilization and a more uniform gel structure, whereas excessive acidification at 2.0% GDL was associated with partial network disruption and water syneresis. Overall, these results indicate that the combined use of pH-shifting and SDF incorporation improved the stability of high-oil emulsions and facilitated the formation of cold-set emulsion gels, providing a useful approach for the valorization of bamboo shoot by-products in plant-based food structuring.