Preparation, safety assessment and application of lanthanum pyrithione-based antimicrobial films for strawberry preservation

Abstract

Food spoilage-induced safety issues represent a significant global challenge, as conventional packaging materials lack antimicrobial functionality to effectively inhibit surface microbial proliferation. Rare earth complex antimicrobial agents offer promising solutions due to their broad-spectrum activity, low toxicity, and excellent thermal stability. The synthesis, characterization, and application of a lanthanum pyrithione (LaPT) complex in antimicrobial films for strawberry preservation were investigated. LaPT was confirmed by FT-IR, XRD, TGA, and SEM to possess a stable chemical structure and excellent thermal stability. Antimicrobial activity was assessed using disk diffusion and minimum inhibitory concentration assays, and significant inhibition of Botrytis cinerea, Escherichia coli, and Staphylococcus aureus was observed. Polyethylene (PE) composite films containing 0.3 % and 0.5 % LaPT were fabricated by melt blending without compromising thermal or mechanical properties. The 0.3 % LaPT film achieved > 99.9 % inhibition of Escherichia coli and Staphylococcus aureus within 24 h. Safety was evaluated by ICP-MS, and migration followed the order acidic > aqueous > alcoholic > fatty food simulants, with a maximum of 15.2 μg/dm², well below EU limits (10 mg/dm²). Cytotoxicity testing yielded an IC₅₀ of 200 μg/mL, acute oral toxicity (LD₅₀: 1.33–1.71 g/kg·bw) indicated low toxicity, and subacute studies revealed no adverse effects. In strawberry preservation trials, LaPT-based antimicrobial films extended shelf life while maintaining fruit quality parameters, supporting their potential for food packaging applications.