Effects of atmospheric cold plasma voltage on the interfacial properties of soy protein isolate-sodium alginate nanoemulsions co-loaded with curcumin and resveratrol and their application in surimi gels during chilled storage.

This study applied atmospheric cold plasma (ACP) at 0-40 kV to prepare curcumin- and resveratrol-loaded SPI-SA nanoemulsions and evaluated their performance in surimi gels. Moderate ACP treatment at 30 kV uniquely optimized the interfacial structure, achieving monomodal droplet size, the highest zeta potential (-56.6 + 0.62 mV) and maximum encapsulation efficiency (curcumin 89.34 ± 0.32%, resveratrol 88.33 ± 0.22%), loading capacity (curcumin 11.91 ± 0.04%, resveratrol 17.66 ± 0.04%), along with superior antioxidant activity (DPPH and ABTS radical-scavenging activities 72.66 ± 1.31% and 67.05 ± 2.21%). Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) confirmed that ACP-induced SPI unfolding, combined with SA enrichment and polyphenol anchoring, promoted a dense hydrogen-bonded interfacial film with enhanced molecular ordering, leading to excellent storage stability and emulsifying properties. In surimi gels, the 30 kV nanoemulsion acted as an optimal active filler, reinforcing the myofibrillar protein network through physical filling and interfacial cross-linking. This resulted in the highest gel strength (3090.05 ± 23.28 g·mm) and water holding capacity (81.51 ± 0.95%), lowest cooking loss (8.20 ± 0.04%) and TBARS values (0.80 ± 0.03 mg MDA/Kg), shortest T₂ relaxation times, and densest microstructure during 15-day refrigerated storage. Unmodified nanoemulsion only provided moderate improvements. Thus, 30 kV is the optimal ACP voltage for preparing stable, high-efficiency nanoemulsions and enhancing surimi gel quality, offering a theoretical basis for ACP-modified protein-polysaccharide delivery systems.