Synergistic antimicrobial effect of ultrasound and carvacrol nanoemulsion against Listeria monocytogenes and its application in cabbage preservation

Abstract

In this study, carvacrol nanoemulsion (CN) was prepared using ultrasonic emulsification and the synergistic bactericidal effect of ultrasound (US) and CN on Listeria monocytogenes and its mechanism were investigated. The results showed that the combined treatment of US and CN had a significant (P < 0.05) synergistic effect on the inactivation of L. monocytogenes, with synergistic values (SV) of 1.345 and 1.325, respectively. US + CN disrupts mononucleosis cell membranes and increases their permeability, as demonstrated by confocal laser scanning microscopy, flow cytometry and cell content release assays. N-phenyl-1-naphthylamine, reactive oxygen species and malondialdehyde assays showed that the combined treatment accelerated cellular oxidative stress and peroxidation, thereby affecting membrane lipid homeostasis. Field emission scanning electron microscopy showed that US + CN caused cell membranes to dry out and crumble. In addition, US + CN effectively kill L. monocytogenes on the surface of cabbages, reduce the weight loss of cabbages during storage, and had no significant (P > 0.05) effect on its color and hardness. This study demonstrated that US + CN has the potential to inactivate foodborne pathogens and improve the safety of fresh produce, providing theoretical possibilities for its application.