Diffusion-controlled release of chemical preservative from chitosan-date seed biocomposites for sustainable antimicrobial poultry meat packaging: A techno-functional valorization of agro-waste.

This study proposes a sustainable active packaging system based on a chitosan-glycerol-date seed powder-sodium benzoate (CHS/DSP/NaBz) composite film designed to enhance meat preservation through controlled antioxidant and antimicrobial release. The optimized formulation (1 % chitosan, 20 % glycerol, 15 % DSP, 5 % NaBz), prepared via solvent casting, produced a homogeneous, flexible matrix, as confirmed by FTIR, SEM, and XRD, which revealed complementary hydrogen bonding and ionic interactions that reduced crystallinity (∼53 % to ∼42 %) and improved structural cohesion. These interactions markedly improved functional properties, including reduced solubility, moisture content, swelling, and WVTR, while maintaining desirable transparency and strong UV-blocking capacity. The ternary film exhibited superior mechanical performance and enhanced thermal stability, indicating suitability for packaging applications. GC-MS and HPLC analyses confirmed the release of volatile glycerides and key phenolics, supporting antioxidant and antimicrobial activity. Release studies demonstrated a biphasic profile, with NaBz showing initial burst release within 5 h and sustained diffusion to 76 % at 96 h in aqueous medium, while DSP phytochemicals reached 83.65 % in 50 % ethanol without initial burst release and saturation kinetics. Kinetic modelling demonstrated that both NaBz and DSP followed a biphasic, diffusion-relaxation-controlled release, with the strongest fits observed for the Korsmeyer-Peppas model (NaBz: R2 = 0.9992, n = 0.53, CI 0.49-0.57; DSP: R2 = 0.9979, n = 0.99, CI = 0.94-1.04), confirming anomalous transport with high confidence and dominant polymer relaxation for DSP and mixed diffusion-relaxation control for NaBz. The CHS/DSP/NaBz film achieved the strongest antimicrobial performance, reducing S. aureus and E. coli to below detectable levels and, in refrigerated chicken packaging, lowered microbial counts from ∼105-106 CFU/mL to <25 CFU/mL, while maintaining colour quality and minimizing lipid oxidation (PV ≈ 3.7 meq O₂/kg; TBARS ≈ 0.52 mg/kg). With ∼65 % biodegradation in 21 days, this valorization of agro-waste highlights a promising, sustainable active packaging solution.