Effect of plastic film packaging on inactivation of foodborne pathogens in hot chili sauce during 915 MHz microwave heating

The objective of this study was to examine how various food-packaging films affect the inactivation of food-borne pathogens in chili sauce when exposed to 915 MHz microwave energy. Polyethylene (PE), polypropylene (PP), nylon (Nylon), and polyether-imide (PEI) films were evaluated. At 3.0 kW, chili sauce sealed in PE, PP, or nylon reached 100℃ in approximately 30 s, whereas PEI-packaged samples required 53 s. A comparable pattern was observed at 1.5 kW. These differences in heating rates translated into distinct pathogen-inactivation kinetics. Chili sauce inoculated with Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes fell below the detection limit within 25 s in PE, PP, and nylon packages at 3.0 kW, but required 40 s in PEI packages to achieve a reduction under 1 log CFU/mL. Microwave treatment caused no significant changes in color or water activity, and volatile compounds such were retained, indicating minimal impact on flavor.