• Fish myofibrillar protein (FMP) was ultrasonicated at 40% amplitude for 15 min. • Ultrasonication (US) induced degradation of myosin heavy chain but not actin. • Ultrasonication altered the β-sheet and the random coil of FMP. • Ultrasonicated FMP (UFMP) was more adsorbed at the interface than FMP. • UFMP improved emulsifying properties and storage stability of emulsion.

Active packaging is an innovative approach to prolonge the shelf-life of food products while ensuring their quality and safety. Carbon dots (CDs) from biomass as active fillers for biopolymer films have been introduced to improve their bioactivities as well as properties. Gelatin/chitosan (G/C) blend films containing active guava leaf powder carbon dots (GL-CDs) at various levels (0–3%, w/w) were prepared by the solvent casting method and characterized. Thickness of the control increased from 0.033 to 0.041 mm when 3% GL-CDs were added (G/C-CD-3%). Young’s modulus of the resulting films increased (485.67–759.00 MPa), whereas the tensile strength (26.92–17.77 MPa) and elongation at break decreased (14.89–5.48%) as the GL-CDs’ level upsurged (p < 0.05). Water vapor barrier property and water contact angle of the film were enhanced when incorporated with GL-CDs (p < 0.05). GL-CDs had a negligible impact on film microstructure, while GL-CDs interacted with gelatin or chitosan, as determined by FTIR. The release of GL-CDs from blend films was more pronounced in water than in alcoholic solutions (10–95% ethanol). The addition of GL-CDs improved the UV light barrier properties and antioxidant activities of the resultant films in a dose-dependent manner. Thus, GL-CD-added gelatin/chitosan blend films with antioxidant activities could be employed as potential active packaging for the food industry.

Active bilayer (BL) packaging films were developed by depositing chitosan/fish gelatin blend containing tannic acid (TA) at varying levels (1, 3, and 5%; w/w) onto a polylactic acid layer. Augmenting TA levels enhanced strength (17.27 MPa to 27.57 MPa) but reduced flexibility (85.03% to ~38%) due to enhanced polymer cross-linking induced by TA, as confirmed by FTIR. The films exhibited exceptional UV-blocking capabilities, in which UVB protection reached 98.34% and 100% for films with 1% and 3% TA, respectively. SEM micrographs revealed uniform dispersion of TA with defect-free matrices. The antioxidant activity of the films upsurged with rising TA levels. When baby clam edible portions (BC-EP) were packed in pouches made with BL films, the pouches containing 5% TA most effectively slowed lipid oxidation and inhibited spoilage during 12 days of refrigerated storage. Total viable count, psychrotrophic bacteria count, and counts of specific spoilage organisms were decreased. Reductions in spoilage bacteria including Shewanella and Pseudomonas and dominance of lactic acid bacteria were confirmed using next-generation sequencing analysis. The release kinetics of TA followed Fickian diffusion, enabling sustained antioxidant and antimicrobial action. TA-containing pouches therefore effectively extended the shelf life of BC-EP through synergistic barrier, antioxidant, and antimicrobial mechanisms, offering a sustainable alternative to conventional plastic packaging.