Development of a Polypropylene-Based Smart Packaging Membrane Using Curcumin and Quercetin for Monitoring Food Freshness

Unlike conventional preservation methods that passively store food, active packaging materials proactively prevent microbial contamination and, when combined with polyphenols, can also serve as intelligent systems for freshness monitoring. In this study, polypropylene (PP)-based membranes incorporating curcumin (Cur) and quercetin (Quer) were developed and characterized to evaluate their potential use in food packaging applications. The membranes exhibited low water vapor permeability, indicating strong barrier properties. Among the formulations, the PP-Cur-A2 (Cur-loaded PP-A2, where A2 refers to chlorinated polypropylene (PP-Cl) obtained from Sigma-Aldrich) membrane showed superior mechanical performance (tensile strength: 24.10 ± 1.06 MPa; elongation at break: 378%) and achieved complete curcumin release within 20 days. Importantly, the membranes displayed distinct color transitions under different pH conditions, confirming their functionality as pH-responsive indicators. In addition, when tested both with fresh shrimp in Petri dishes and in aqueous ammonia environments, the membranes exhibited visible and progressive color changes in response to spoilage-related volatile compounds. Overall, the developed membranes demonstrated efficient bioactive release, excellent barrier characteristics, and reliable colorimetric indicator functionality, underscoring their promise for sustainable and intelligent food packaging applications.