Efficacy of Commercial Natural Antimicrobials Alone and in Combinations against Pathogenic and Spoilage Microorganisms

Microbial control strategies are needed in the food industry to prevent foodborne illnesses and outbreaks and prolong product shelf life. The aim of this study was to investigate and compare the efficacy of the commercial natural antimicrobials white mustard essential oil (WMEO), citrus flavonoid and acid blend (CFAB), olive extract (OE), Nisaplin (a compound containing nisin), and lauric arginate (LAE) alone and in combinations against foodborne pathogens and spoilage microorganisms. MICs of individual and combined antimicrobials against Escherichia coli, Salmonella Enteritidis, Enterobacter aerogenes, Bacillus cereus, Listeria monocytogenes, and Staphylococcus aureus were determined at pH 6.0 and 25°C. WMEO was most effective against B. cereus and S. aureus, with MICs of 250 and 500 mg/liter, respectively. CFAB inhibited all tested microorganisms, requiring only 12 to 35 mg/liter for gram-positive bacteria. For OE, 2,000 mg/liter was needed to achieve microbial inhibition. Nisaplin at 400 to 1,200 mg/liter inhibited only gram-positive bacteria. LAE was effective at low concentrations and required only 20 to 50 mg/liter to inhibit all tested microorganisms. When WMEO was combined with other antimicrobials, the effects were usually additive except for WMEO plus Nisaplin and WMEO+OE, which had synergistic activity against L. monocytogenes and Salmonella Enteritidis, respectively. An antagonistic effect was observed for WMEO+CFAB against E. aerogenes. For WMEO+LAE+CFAB, additive antimicrobial effects were noted against all strains tested except S. aureus, where a synergistic effect occurred. These findings suggest that these commercial natural antimicrobials have potential to enhance food safety by inhibiting foodborne pathogens and extending product shelf life.