Probing the Physicochemical, Nanomorphological, and Antimicrobial Attributes of Sustainable Silk Fibroin/Copaiba Oleoresin-Loaded PVA Films for Food Packaging Applications

We explore the development of biodegradable poly(vinyl alcohol) (PVA) films loaded with silk fibroin (SF) functionalized with copaiba oleoresin (SFCO) for potential use in active food packaging. The films were characterized, showing significant improvements in both their physicochemical and nanomorphological properties. Films containing 10% SFCO exhibited superior mechanical strength, with a Young modulus of 145 MPa and an elongation at break of 385%, compared to the control film with 42 MPa and 314%, respectively. The films also demonstrated barrier properties, with water vapor transmission rates (WVTRs) as low as 25.95 g/h·m2. Antimicrobial activity against Staphylococcus aureus and Escherichia coli was significantly improved, showing inhibition zones of up to 10 ± 1 mm and a minimum inhibitory concentration (MIC) of 100 µg∙mL−1. Three-dimensional nanomorphological analysis via atomic force microscopy (AFM) showed increased roughness in films with higher SFCO content, with root mean square (RMS) roughness values ranging from 2.70 nm to 11.5 nm. These results highlight the potential of SFCO-loaded PVA films as robust, eco-friendly alternatives to conventional packaging materials. They provide improved mechanical and antimicrobial properties, essential for extending the shelf life of perishable foods and advancing sustainability in the packaging industry.