Eco-friendly intelligent packaging film from dragon fruit peel pigment extract for real-time seafood freshness monitoring

Tóm tắt

Environmental concerns over persistent plastic waste have driven the development of biodegradable alternatives for food packaging. In this study, a pH-responsive biodegradable indicator film was fabricated from sodium alginate and starch, incorporated with a pigment-rich extract (betalain/anthocyanin mixture) obtained from dragon fruit (Hylocereus spp.) peel. Films were prepared at various sodium-alginate-to-starch ratios and pigment loadings, and their physicochemical, mechanical, thermal, and biodegradation properties were evaluated. The optimized formulation (SA:S = 3:7) exhibited the highest tensile strength (~21 MPa), balanced water resistance, and favorable swelling behavior. Thermal analysis revealed that the composite films exhibited enhanced stability compared to pure sodium alginate films, while biodegradation assays demonstrated a mass loss of up to 59% within 30 days under natural conditions. The pigment-containing films displayed distinct pH-dependent color changes, enabling real-time visual monitoring of shrimp freshness. Under room-temperature storage, the film changed from red to bluish-yellow after four days, corresponding to a TVB-N value of 30.1 mg/100 g, indicating complete spoilage. These findings suggest that sodium alginate– starch–pigment films are promising, eco-friendly intelligent packaging materials for freshness indication.