Essential oils (EOs) are natural compounds found in many plant products known to possess antimicrobial and bioactive properties. However, their hydrophobicity and strong sensorial characteristics present challenges for incorporating these compounds into food systems. One proposed solution to this challenge is encapsulation of oils using synthetic or other natural compounds such as emulsifiers. Previous research has shown that soy lecithin, a generally recognized as safe (GRAS) emulsifier, can enhance the antimicrobial efficacy of eugenol on Escherichia coli. The objective of this study was to determine if a similar synergistic effect exists between lecithin and eugenol on Listeria monocytogenes. At a constant eugenol concentration, levels of lecithin from 0.5-40mg/100 ml did not enhance antimicrobial activity of eugenol and resulted in lower levels of bacterial reduction than eugenol-only controls. These results may be due to the Gram-positive cellular membrane of L. monocytogenes, as EO mechanisms of action likely involve interactions between the oil and cell surface components. In the future, microscopy techniques such as cryo-TEM can be utilized to study how lecithin-eugenol droplets may be affecting bacteria in solution.
