Intelligent film based on mulberry anthocyanin, sodium alginate, and gellan gum for monitoring pork freshness

A novel sodium alginate/gellan gum-based composite film with mulberry anthocyanins (MAE) as an indicator was developed for real-time pork freshness monitoring. Research showed that the incorporation of MAE significantly improved the physical properties of the composite films, increasing the tensile strength (25.2 %), elongation at break (24.6 %), and thickness (30.4 %). FT-IR, X-RD, and SEM analyses indicate that the compatibility and molecular interactions between MAE and polymer matrix have been enhanced. The composite films exhibited pH-responsive behavior, demonstrating distinct color changes in buffer solutions across a pH range of 2–12. When used to evaluate the freshness of pork, the composite film will show a significant color change, which is consistent with the texture of the pork. The color difference of the films showed a strong linear relationship with the storage time of the pork, total volatile basic nitrogen (TVB-N), and pH. Therefore, composite films showed great potential for application as smart packaging in monitoring pork freshness. • Mulberry anthocyanins (MAE) significantly improve the mechanical properties of sodium alginate/gellan gum (SA/GG) films. • A noticeable colour change (ΔE >12) can be observed with the naked eye, transitioning from red (pH 2) to yellow (pH 12). • The strong correlation (R 2 > 0.92) between film color and spoilage indicators of pork enables effective spoilage detection.