The synergistic antimicrobial effects and mechanism of cinnamon essential oil and high voltage electrostatic field and their application in minced pork

Spice essential oils (EOs) have potent antimicrobial ability, but their application as food preservatives was severely limited by strong sensory properties. In this study, high voltage electrostatic field (HVEF) was applied to strengthen the antimicrobial effect of EOs while reducing their additive dosage. First, cinnamon essential oil (CEO) was selected from ten spice EOs because of its strongest inhibition against bacteria (Escherichia coli and Staphylococcus aureus) and molds (Penicillium citrinum and Aspergillus niger) common in foods. Then, the antimicrobial effect and mechanism of CEO and HVEF used alone or in combination were investigated. The results exhibited that the antimicrobial effect of CEO was dramatically enhanced by combining with HVEF, as the required concentration for the same antimicrobial effect was only 1/4∼1/3 of that when used alone. Both CEO and HVEF treatments changed the permeability of the microbial cell wall as well as the permeability and integrity of the cell membrane, resulted in the change in membrane protein structure, led to the increase in content of reactive oxygen species in the microbial cells, while the combined treatment of HVEF and CEO (HVEF + CEO) caused the significantly greater effect on microbes than two treatments applied alone. Finally, HVEF was found to substantially improve the preservative effects of CEO, allowing CEO to prolong the shelf life of minced pork from about 3 d to 7 d without compromising its original sensory quality.