Developing ethyl lauroyl arginate antimicrobial films to combat Listeria monocytogenes in cured ham
Widespread use of plastics poses a serious environmental hazard to our planet and should be substituted by eco-friendly and biodegradable alternatives, simultaneously reducing waste of perishable food products and the risk of transmission of pathogenic microbes. In our study, we describe how the water solubility of the antimicrobial surfactant ethyl lauroyl arginate (LAE) can be reduced through complexation with a Keggin-type polyoxometalate (POM), K8[SiW11O39]. The POM-LAE complex, LAE7K[SiW11O39], was effective against Listeria monocytogenes (L. monocytogenes) and Escherichia coli (E. coli) with minimal inhibitory concentrations (MICs) of 32 and 64 μg/mL, respectively, with the important finding that the concentrations of LAE required to inhibit bacterial growth were as much as two times lower in the POM-LAE complex, compared with LAE on its own. In addition, our results demonstrate that POM-LAE is both an effective inhibitor of biofilm formation and is also able to destroy pre-formed biofilms of L. monocytogenes and E. coli at MIC concentrations. Further, POM-LAE was incorporated into carboxymethyl cellulose (CMC) films that were able to reduce 7–8 log (CFU/mL) of L. monocytogenes at concentrations of 5–10% POM-LAE. In vivo assays of the POM-LAE-CMC films with cured ham prevented initialk bacterial growth with a 0.77 log significative reduction in bacterial counts. Overall, this work provides new alternatives for the development of antimicrobial biodegradable films for ready-to-eat (RTE) foods prone to contamination with pathogenic bacteria, such as L. monocytogenes, while also circumventing practical issues related to the incorporation of LAE into active packaging films.