Impact of cinnamaldehyde nanoemulsion on Listeria monocytogenes biofilms on broth-treated food contact surfaces

Abstract

Listeria monocytogenes (L. monocytogenes) is a foodborne pathogen that forms biofilms, causing persistent contamination and health risks. Cinnamaldehyde nanoemulsion (CAN), a stable and broad-spectrum antimicrobial, was investigated for its effect on L. monocytogenes biofilms. CAN showed good stability with particle sizes below 200 nm. At 28 °C, L. monocytogenes biofilms were more prevalent than at 37 °C. CAN significantly inhibited L. monocytogenes, with an MIC of 0.5 mg/mL, and its bactericidal effect increased over time and with concentration, achieving over 90.0% inhibition and removal. CAN effectively removed L. monocytogenes biofilms on various food contact materials, especially stainless steel, with the highest removal rate reaching 82.4%. Broth treatment altered L. monocytogenes adhesion, reducing it on stainless steel and increasing it on plastics, suggesting CAN's suitability for stainless steel. Interestingly, the removal efficacy of CAN is substantially augmented under the influence of broth, with an increase of 1.0%–23.0% across materials. The adhesion and removal efficacy were linked to material hydrophobicity, with stainless steel showing more pronounced effects due to its relative hydrophilicity. These insights are crucial for developing more effective disinfection strategies for food contact surfaces.