Chitosan-Based Active Films Enriched with Thyme Essential Oil for Extending the Shelf Life of Refrigerated Chicken Meat

The development of biodegradable active packaging systems incorporating natural antimicrobial and antioxidant compounds represents a promising strategy for improving the quality and shelf life of fresh meat. This study aimed to develop chitosan (CH)-based active films containing thyme essential oil (TEO) at 0%, 2.5%, and 3%, and to evaluate their antimicrobial and antioxidant properties and effectiveness in preserving chicken breast fillets during refrigerated storage. The chemical composition of TEO was characterised by gas chromatography–mass spectrometry, identifying 29 compounds, with p-cymene (30.56%) and thymol (24.59%) as the predominant constituents. Undiluted TEO showed strong antimicrobial activity against E. coli and L. innocua. The incorporation of 2.5% and 3% TEO into CH films increased the inhibition percentage and microbial susceptibility and also enhanced their antioxidant activity. The performance of the films was subsequently assessed using chicken breast fillets stored at 5 °C for 1, 3, and 5 days. All CH-based systems reduced microbial growth compared with uncoated controls, which exceeded 6–7 log CFU g−1 for several microbial groups after 5 days. CH-based packaging also reduced protein oxidation and maintained low lipid oxidation. However, 3% TEO caused significant colour deterioration by day 5. These results demonstrate the potential of CH-based active films enriched with TEO as a natural and biodegradable packaging alternative to enhance the shelf life and safety of refrigerated chicken meat.