Special Characterization and Excellent Antioxidant Capabilities of Zinc Chelated Squid Protein Nanoparticles

The functional exploration of marine-derived proteins is at the forefront of nutritional research. The Argentine squid protein (ASP) was extracted from Argentine squid carcasses and was hydrolyzed using neutral protease, with the degree of hydrolysis serving as the response variable. Using single-factor experiments and response surface methodology, we identified optimal conditions for preparing Argentine squid protein peptides (ASPP). The hydrolysis degree reached 41.32% ± 0.27 under the conditions of 7% enzyme preparation addition, 2.4 h enzyme digestion time, and 6% substrate concentration. The ASPP was subsequently chelated with zinc sulfate to produce Zn-ASPP, whose structural and functional properties-including particle size, FTIR, DSC, viscosity, SEM, solubility, emulsibility, foamability, and antioxidant capacity-were systematically characterized. The results indicate that Zn-ASPP forms stable nanoparticles with strong antioxidant activity. The strongest antioxidant capacity reached 73.79% at a solution pH of 8, making it particularly valuable for food industry applications. This work may provide a theoretical basis and practical guidance for the development of zinc-fortified marine protein supplements with enhanced antioxidant properties.