The Effect of the DBD Cold Plasma Process on the Physicochemical, Mechanical, and Microbial Properties of the Biodegradable Packaging Film (Based on Gelatin-Sodium Alginate) Incorporated with AgNPs to Extend the Shelf Life of Trout Fish in the Refrigerator

This investigation aimed to develop a novel biodegradable packaging film based on gelatin (G) and sodium alginate (SA) biopolymers containing silver nanoparticles (AgNPs) using the solvent casting method, assess the physicochemical, mechanical, and antimicrobial features, and evaluate the efficacy of the films in food packaging consumption. Film properties were slightly affected by AgNP concentration levels. As the concentration of AgNPs was increased, water vapor permeability (WVP), water solubility, transparency, and tensile strength (TS) of GSA-AgNPs films were significantly reduced by an average of 42%, 59%, 56%, and 76%, respectively (p < 0.05). Additionally, the impacts of Hurdle technology on GSA (control) and GSA-AgNPs (optimal) films were investigated using dielectric barrier discharge (DBD) cold plasma technology. Scanning electron microscopy (SEM) revealed that cold plasma-treated GSA-AgNPs films had compact surface structures, excellent structural integrity, good barrier qualities, and potential antibacterial activity (Escherichia coli O157:H7 and Salmonella Typhimurium) as a result of DBD cold plasma treatment. The packaged samples with cold plasma-treated optimal films were lower in thiobarbituric acid (0.54 mg MDA/kg sample), total volatile nitrogen (19.04 mg/100 g), and total mesophilic bacteria count (5.8 log CFU/g) compared to other samples. Tests on fish fillets have indicated that cold plasma-treated films containing 20 ppm (0.002%) AgNPs are considered the most effective antimicrobial food packaging.