Antimicrobial essential oil component (EOC)-containing micelles assist the delivery of natural food antimicrobials to food surfaces, including fresh produce, for decontamination of microbial foodborne pathogens. Antimicrobial EOC-loaded micelles were able to inhibit the enteric pathogens Escherichia coli O157:H7 and Salmonella Saintpaul in liquid medium and on spinach surfaces. However, pathogen reduction generally was not impacted by the method of micelle application (spraying, immersion washing) on spinach surfaces.

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The plant‐derived essential oil component eugenol (1.0% wt/vol), free or loaded into surfactant micelles constructed of sodium dodecyl sulfate (SDS; 1.0% wt/vol), 200 ppm free chlorine (hypochlorous acid [HOCl]; pH 7.0), and sterile distilled water were evaluated for their ability to reduce Salmonella Saintpaul and Escherichia coli O157:H7 on skin surface samples of Roma tomatoes. Samples were treated and then stored aerobically for up to 10 days. All samples were initially stored at 5 °C; one set of samples was shifted to 15 °C after 5 days of storage to simulate temperature abuse during postharvest handling. Encapsulated and free eugenol, HOCl, and empty SDS micelles reduced pathogens to nondetectable counts (detection limit: 0.5 log10 cfu/cm2) during refrigerated storage (p ≥ .05). Conversely, during temperature abuse storage (15 °C), only free and micelle‐loaded eugenol consistently reduced pathogens to nondetection. Eugenol‐loaded micelles can be used to decontaminate harvested tomatoes from enteric bacterial pathogens. Practical applications Tomatoes may be consumed raw and have been repeatedly implicated in the occurrence of human foodborne disease. Washing of tomatoes with novel antimicrobial interventions that increase the dispersion of antimicrobials over the surface of the tomato should result in greater reduction of microbial foodborne pathogens through enhanced contact of antimicrobial with pathogen. Application of surfactant micelle‐entrapped eugenol onto tomato surfaces reduced Salmonella Saintpaul and Escherichia coli O157:H7 to nondetection during refrigerated (5 °C) and temperature abuse (15 °C) storage. Micelle‐loaded eugenol reduced numbers of aerobic bacteria, Enterobacteriaceae, and fungi to nondetection during temperature abuse storage.

Spinach and other leafy green vegetables have been linked to foodborne disease outbreaks of Escherichia coli O157:H7 and Salmonella enterica around the globe. In this study, the antimicrobial activities of surfactant micelles formed from the anionic surfactant sodium dodecyl sulfate (SDS), SDS micelle-loaded eugenol (1.0% eugenol), 1.0% free eugenol, 200 ppm free chlorine, and sterile water were tested against the human pathogens E. coli O157:H7 and Salmonella Saintpaul, and naturally occurring microorganisms, on spinach leaf surfaces during storage at 5 °C over 10 days. Spinach samples were immersed in antimicrobial treatment solution for 2.0 min at 25 °C, after which treatment solutions were drained off and samples were either subjected to analysis or prepared for refrigerated storage. Whereas empty SDS micelles produced moderate reductions in counts of both pathogens (2.1–3.2 log10 CFU/cm2), free and micelle-entrapped eugenol treatments reduced pathogens by >5.0 log10 CFU/cm2 to below the limit of detection (<0.5 log10 CFU/cm2). Micelle-loaded eugenol produced the greatest numerical reductions in naturally contaminating aerobic bacteria, Enterobacteriaceae, and fungi, though these reductions did not differ statistically from reductions achieved by un-encapsulated eugenol and 200 ppm chlorine. Micelles-loaded eugenol could be used as a novel antimicrobial technology to decontaminate fresh spinach from microbial pathogens.

Beef safety may be compromised by O157 and non-O157 Shiga toxin-producing Escherichia coli (STEC) contamination. The capacity of surfactant micelles loaded with the plant-derived antimicrobial eugenol to reduce STEC on beef trimmings that were later ground and refrigerated for five days at 5 ± 1 °C was tested to determine their utility for beef safety protection. STEC-inoculated trimmings were treated with free eugenol, micelle-encapsulated eugenol, 2% lactic acid (55 °C), sterile distilled water (25 °C), or left untreated (control). Following treatment, trimmings were coarse-ground and stored aerobically at 5 ± 1 °C. Ground beef was then sampled for STEC immediately post-grinding, and again at three and five days of storage. STEC minimum inhibitory concentrations (MICs) in liquid medium for free eugenol and 1% sodium dodecyl sulfate (SDS)-loaded micelles were 0.5% and 0.125%, respectively. STEC numbers on beef trimmings treated by sterile water (6.5 log10 CFU/g), free eugenol (6.5 log10 CFU/g), micelle-loaded eugenol (6.4 log10 CFU/g), and lactic acid (6.4 log10 CFU/g) did not differ compared to untreated controls (6.6 log10 CFU/g) (p = 0.982). Conversely, STEC were significantly reduced by refrigerated storage (0.2 and 0.3 log10 CFU/g at three and five days of storage, respectively) (p = 0.014). Antimicrobial treatments did not significantly decontaminate ground beef, indicating their low utility for beef safety protection.