Multifunctional RP/SA bilayer film with oregano essential oil and anthocyanins: Properties enhancement mechanism and...

This study aimed to develop a multifunctional bilayer film with a pectin/anthocyanin indicator layer and an oregano essential oil (OEO)/rice protein/sodium alginate active layer for prolonging pork shelf life and monitoring freshness. The film at optimal layer mass ratio (1:1) exhibited enhanced tensile strength (6.67 MPa) and elongation at break (17.73 %). The addition of OEO significantly improved the water vapor-, oxygen- and light-barrier properties. Molecular dynamics simulations showed that OEO promoted the formation of hydrogen bonds (from 9 to 11) between film components, resulting in a compact structure and enhanced properties. The film with OEO concentration ≥ 1.2 % displayed strong antimicrobial and antioxidant activities. The bilayer film extended pork shelf life by at least 2 days and distinguished freshness by color change. This work integrates colorimetric sensing with active protection and achieves concurrent improvements in mechanical and barrier performance, underscoring its potential to monitor spoilage and extend meat shelf life.