Resazurin-impregnated gelatin-based indicator for intelligent packaging applications

Abstract

Modified resazurin (Res) incorporating gelatin (Gel) based indicator films were prepared to monitor the quality of packed shrimp in real time. FE-SEM micrographs show uniform dispersion of Res with minimal irregularities in the indicator film. The integration of Res increased the film's load-bearing ability and tensile strength without affecting the film's transparency and water vapor permeability. FT-IR and XPS profiles showed high compatibility and intermolecular H-bonds between the Res and Gel polymer matrices. The release rate of Res from the Gel-Res indicator film depended on the food simulant showing higher release rates in aqueous solutions (water and 10% ethanol) than in alcohol solutions (50% and 95% ethanol solutions). The Gel-Res indicator film exhibited excellent color stability even after storage for 60 days at room temperature. It was sensitive to ammonia vapor and alkaline pH solutions with a color change from yellow to pink with a total color difference (ΔE) of 15.4. In shrimp packaging tests, Gel-Res films exhibited noticeable color changes, which corresponded well with TVB-N levels and pH changes. These results suggest that the Gel-Res indicator films have acquired ideal prerequisites for potential intelligent seafood packaging.