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Double-layered active films based on furcellaran (1st layer—FUR), chitosan, and gelatin hydrolysates (2nd layer—CHIT+HGEL) were successfully prepared. Bioactive ingredients were added to the 1st film layer: AgNPs, which were synthesized in situ with yerba mate extract; montmorillonite clay (MMT); and different loads of ethanolic curcumin (CUR) extract enriched with rosemary essential oil (REO). SEM images confirmed the presence of AgNPs with a size distribution of 94.96 ± 3.33 nm throughout the films, and AFM and SEM photos indicated that the higher substance concentrations had rougher and more porous film microstructures. However, the water vapor transmission rate was reduced only at the lowest load of this ingredient. Despite the tensile strength of the films having decreased, the incorporation of the compounds showed a tendency towards reducing the modulus of elasticity, resulting in a lower stiffness of the composites. The addition of CUR and AgNPs improved the UV light barrier properties of the materials. The presented films showed quick reactions to changes in the pH value (from orange to red along with an increase in pH from 2 to 10), which indicates their potential use as indicators for monitoring the freshness of food products. Composite No. 2 showed the highest antimicrobial potential, while none of the presented films showed an antifungal effect. Finally, the antioxidant activities of the films increased dramatically at higher AgNP and CUR loads, suggesting an outstanding potential for active food packaging applications. [ABSTRACT FROM AUTHOR]

• The double-layer furcellaran/gelatin hydrolysate and Ala-Tyr dipeptide film were developed. • The addition of peptide improved antioxidant and properties of the film. • The properties of films were tested on fish carcasses during frozen storage. • The application of films on the fish did not significantly inhibit oxidation rate. This is the first time that active double-layered furcellaran/gelatin hydrolysate films containing Ala-Tyr peptide were developed and characterised for their properties. Afterwards, films were used on Atlantic mackerel stored at −18 °C for 4 months and samples were analysed for changes in their microbiological quality, TVB-N, biogenic amine content, fatty acid composition and TBARS. Active films had higher TS (13.4 MPa) and lower WS (62.8%). The films showed no DPPH radical scavenging properties but high FRAP (6.6 mMol Trolox/mg). No significant effects on the oxidation of fish samples were observed with TBARS increasing from 12.04 to 22.50 mg/kg. Freezing successfully inhibited the growth of microorganisms and no differences in microbiological growth or biogenic amine formation were observed. However, the application of films inhibited the formation of TVB-N. Antimicrobiological properties of the film should be further investigated during storage of perishable food products at temperatures above 0 °C. [ABSTRACT FROM AUTHOR]