Development of Intelligent and Active Gelatin-Based Packaging Film Incorporating Red Onion Anthocyanins and...

With rising living standards, consumer demand for fresher food continues to increase. Consequently, the development of multifunctional packaging materials that enable real-time freshness monitoring, delay spoilage, and ensure environmental sustainability has become a central research focus. The present study developed an antibacterial and pH-responsive smart packaging film, formulated from a κ-carrageenan/gelatin (CG) matrix. This film incorporated anthocyanins extracted from red onion skin (ROSA) and citronella essential oil encapsulated in β-cyclodextrin (OBDs) as functional additives, herein referred to as the CGR/OBDs composite film. The composite films exhibited strong pH sensitivity, ammonia responsiveness, color stability, effective barrier properties, and notable antioxidant activity (96.4% ABTS and 79.3% DPPH radical scavenging rates). The sustained release of citronella essential oil over approximately 40 h conferred excellent antibacterial performance, with inhibition rates of 94.8% against Staphylococcus aureus (S. aureus) and 91.6% against Escherichia coli (E. coli). Application in shrimp preservation further demonstrated an extended shelf life and real-time freshness monitoring through distinct colorimetric shifts. The findings highlight the potential of CGR/OBDs films as visual indicators for food freshness in intelligent packaging, offering a promising strategy to enhance food safety and reduce waste.