Sustainable Active Packaging Based on Chitosan–Pomegranate Peel Biofilm Protects Pecorino Romano PDO Cheese Through Polyphenol-Driven Antioxidant and Antimicrobial Activity

A chitosan-based edible biofilm enriched with pomegranate peel extract and essential oils was developed as a sustainable active packaging material that exploits agro-industrial by-products, in agreement with circular economy principles. Targeted HPLC–MS/MS analysis quantified twelve polyphenols, with total polyphenol content ranging from 88.20 to 137.38 μg/g dry weight. Ellagic acid was the predominant compound (90.78 μg/g dry weight), followed by gallic acid (28.80 μg/g dry weight). Untargeted HPLC–HRMS analysis revealed additional flavonoid and ellagitannin-related derivatives, confirming the chemical complexity of the incorporated phenolic fraction. ICP-OES analysis showed heavy metal concentrations below the analytical quantification limits, supporting compliance with food-contact safety requirements. During 45 days of refrigerated storage, coated Pecorino Romano PDO cheese exhibited lower yeast and mold counts than uncoated controls, with a maximum reduction of approximately 0.87 log10 CFU/g. Enterobacteriaceae remained below the detection limit in coated samples throughout storage, whereas they were detected in untreated cheese at the end of storage. These findings demonstrate the potential of the developed edible biofilm as a safe and sustainable active packaging material for refrigerated dairy products while promoting the valorization of pomegranate processing by-products.