Monitoring Shrimp Spoilage Using a Paper-based Colorimetric Label Containing Roselle Flower Extract

Background: Intelligent food packaging that can monitor food quality and safety is essential in modern commercial trade. Research on the fabrication of environmentally friendly colorimetric labels that can indicate the freshness of food through color changes are needed. Methods: In this study, paper-based colorimetric labels were prepared using filter paper dipped into a solution of Roselle flower extract, and their performance in monitoring shrimp spoilage was investigated. Results: The labels’ response to ammonia vapor shows a distinct color variation from red to greenish-grey, corresponding to a sharp increase in the total color difference (ΔE = 32). The labels are relatively stable during storage at 4°C for up to 20 days. In shrimp freshness monitoring, the color changes from red to purple, which corresponds to increasing levels of total volatile basic nitrogen (TVB-N), and can be observed easily with the naked eye. Conclusion: This suggests that our paper-based colorimetric labels impregnated with Roselle extract show superior performance in detecting shrimp spoilage.