The Effect of Lecithin on Inactivation by Eugenol of <i>Escherichia coli</i> O157:H7

Many essential oils and their components are known to have antimicrobial activity. However, their strong aroma, flavor, and hydrophobic nature make them difficult to incorporate into food products. New methods to improve antimicrobial activity at reduced concentrations and/or reduce the influence of food components on antimicrobial activity are needed. In this study, the objective was to combine the emulsifier soy lecithin with eugenol in an attempt to enhance the activity of the latter against the foodborne pathogen Escherichia coli O157:H7.

Eugenol was added to a pH 7.2 sodium phosphate buffer (PBS), PBS with 0.03% (v/v) tryptic soy broth (TSB), PBS with 0.3% TSB, PBS with 0.6% TSB or PBS with 0.9% TSB and lecithin solution (0.0025, 0.005, 0.010, or 0.015% (w/v)) and homogenized at 10,000 rpm for 3 min. An overnight culture of Escherichia coli O157:H7 was added and survivors enumerated at 0, 1, 3, 6, 12, and 24 h on tryptic soy agar (TSA) incubated for 24 h at 37°C. The effect of varying microbiological media concentrations (0.03-0.09% w/v) on lecithin interaction with eugenol was also evaluated.

In buffer with 550 ppm of eugenol, 0.01% lecithin slightly increased the effectiveness of eugenol (P