Dual-Mode Antimicrobial Sachets: Polyethylene Glycol-Plasticized Polylactic Acid Carriers Loaded with EDTA or Ethyl maltol for Preservation of Packaged Foods

Active packaging inserts can reduce microbial spoilage when antimicrobial release is matched to the food surface or package headspace. This study developed poly(lactic acid) (PLA) pelletized carriers plasticized with poly(ethylene glycol) (PEG; 5 or 10 wt.%) and loaded with either ethylenediaminetetraacetic acid (EDTA; 5 wt.%, non-volatile) or ethyl maltol (EMT; 5 wt.%, volatile) for antimicrobial sachet applications. Compared with our previous direct-contact PLA sheets, this work examines how the same active compounds behave after conversion to pellet-filled sachets, enabling comparison between moisture-assisted contact release of EDTA and vapor release of EMT. SEM, NMR, FTIR, DSC and TGA suggested improved compatibility after PEG addition, with stronger plasticization in PEG–EMT blends than in PEG–EDTA blends. In broth culture, PLA–PEG–EDTA sachets showed higher antibacterial activity against Staphylococcus aureus and Escherichia coli , whereas PLA–PEG–EMT sachets showed stronger antifungal activity against Aspergillus niger and Penicillium sp. GC–MS showed temperature-dependent EMT release, including slower release at 4 °C. In food model tests, EDTA-based sachets reduced total viable counts in refrigerated salmon during 3 days of storage, while EMT-based sachets reduced yeast and mold growth in salami during the tested period. These results indicate that PEG-plasticized PLA sachets can be tuned toward either contact-assisted antibacterial action or vapor-dominant antifungal action, depending on the antimicrobial compound. • PEG-plasticized PLA enabled dual contact and vapor antimicrobial packaging. • PLA-PEG-EDTA exhibits antibacterial activity against S. aureus better than E. coli. • Both contact and vapor phase antifungal activity were achieved by PLA-PEG-EMT sachet. • Sachets with PLA-PEG-EDTA effectively reduces bacterial growth in salmon fillets. • Mold growth and spore formation in salami could be controlled by PLA-PEG-EMT sachet.