Development of gelatin–sodium caseinate high-oxygen-barrier film containing elderberry (Sambucus nigra L.) extract and its antioxidant capacity on pork

The use of biodegradable polymers and natural additives is a sustainable strategy to prevent oxidation and extend food shelf life. In this study, a gelatin–sodium caseinate composite film containing elderberry extract was newly developed and characterized. The film with the most optimal oxygen permeability and water vapor permeability was selected by blending gelatin (G) and sodium caseinate (S) at a 50:50 ratio (w/w). The addition of 0.5% (w/w) elderberry extract (EE) improved the oxygen barrier properties and gave the edible film a high potential for food quality preservation. Elongation was improved (105.82% ± 9.36%) and DPPH radical scavenging analysis revealed a significantly strong antioxidant activity (P < 0.05). FT-IR spectra and SEM indicated that it is the result of polyphenols and other EE components interacting with the protein matrix. The developed film was applied as a coating and significantly prevented weight loss of pork after 12 h at room temperature (Control, 0.18% ± 0.01%; G50:SC50, 0.11% ± 0.01%; G50:SC50 + EE0.5, 0.11% ± 0.02%; P < 0.05). The EE-containing G50:SC50-coated pork showed the lowest lipid oxidation as measured by TBARS after 36 h (0.36 ± 0.06 mg MDA/kg sample). This finding suggested that it was related to polymorphic mechanisms, including radical scavenging and oxygen contact blocking. Therefore, protein-based films containing natural extract have the potential for an antioxidant packaging strategy.