Inhibition of Bacterial Pathogens in Medium and on Spinach Leaf Surfaces using Plant‐Derived Antimicrobials Loaded in Surfactant Micelles

Abstract

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.

Inhibition of bacterial human pathogens on tomato skin surfaces using eugenol‐loaded surfactant micelles during refrigerated and abuse storage

“…At the critical micelle concentration, a surfactant will self‐assemble into thermodynamically favored aggregates, such as micelles and liposomes (McClements, ). Previous studies have shown encapsulation of EOCs in surfactant micelles improved the dispersion of EOCs in aqueous fluids, resulting in improved inhibition of foodborne pathogens in foods, including fresh produce (Kang & Song, ; Park et al, ; Pérez‐Conesa, Cao, Chen, McLandsborough, & Weiss, ; Ruengvisesh, Loquercio, Castell‐Perez, & Taylor, ; Zhang, Critzer, Davidson, & Zhong, ).…”

Application of Surfactant Micelle-Entrapped Eugenol for Prevention of Growth of the Shiga Toxin-Producing Escherichia coli in Ground Beef

“…Similar MICs for other plant-derived antimicrobials against E. coli O157:H7 and other Enterobacteriaceae have been reported elsewhere [ 25 , 26 ]. Previous research has also demonstrated enhanced antimicrobial efficacy of plant essential oil components following micelle entrapment in complex food matrices, reportedly resulting from enhanced dispersion of the hydrophobic oils into the aqueous fraction of the food and transport of essential oil components into the membrane of STEC isolates and other bacterial organisms [ 16 , 18 , 25 , 27 , 28 ]. Refrigerated storage is not expected to have significantly inhibited eugenol release by SDS micelles, given previous reports in which a 4.1 log 10 -cycle reduction of Salmonella Enteritidis was reported during a 5 min exposure to 1% SDS/levulinic acid micelles at 8 °C [ 19 ].…”

“…The working stock was stored at 5 ± 1 °C in a foil-wrapped container until ready for use. Following calculation of required eugenol and surfactant for micelle generation [ 16 ], eugenol in alcohol and surfactant in sterile water were mixed and brought to volume with sterile distilled water as required. Mixtures were stirred at room temperature to form micelles.…”

“…Determination of STEC isolate-specific MICs for free and micelle-loaded eugenol was completed according to published methods [ 16 ]. Microplate wells containing individual STEC isolates were exposed to free or encapsulated eugenol at 2-fold serial dilutions and then incubated for 24 h at 35 ± 1 °C.…”

“…More recently, researchers reported that the application of 0.05% or 0.1% rutin, or 0.1% or 0.2% resveratrol, did not reduce E. coli O157:H7 in ground beef patties during refrigerated storage, but did enhance reductions of the pathogen upon subsequent cooking to an internal temperature of 65 °C [ 15 ]. The use of encapsulation strategies, such as surfactant micelles, has been described as providing opportunity for enhanced transport and delivery of entrapped compounds to foodborne microbes in both animal- and plant-based foods [ 16 , 17 , 18 ]. The use of micelle-encapsulated eugenol for reducing O157 or non-O157 STEC on fresh beef has not, to the authors’ knowledge, been reported in the scientific literature.…”