New Approach to Study the Mechanism of Antimicrobial Protection of an Active Packaging

Abstract

This article reports on the antimicrobial efficiency of a new active packaging concept based on the use of two essential oils (cinnamon and oregano) and their chemical descriptors (cinnamaldehyde, thymol, and carvacrol) against the Gram-positive bacterium Listeria monocytogenes, the Gram-negative bacterium Salmonella choleraesuis, the yeast Candida albicans, and the mold Aspergillus flavus. Complete inhibition of these microorganisms with either bactericidal or bacteriostatic effect has been demonstrated. It has been proven that the inhibition provided by these solutions is related not to the total amount of the active chemical released but to the amount of active compounds that reach the agar surface at a critical time. This critical time is notably related with the duration of the lag phase, as demonstrated for the bacteria, and shows that kinetic behavior has a critical role in the antimicrobial properties of the active packaging. Two different active films, polypropylene and the complex polyethylene-ethylenvynil alcohol, have been studied and a higher efficiency was found for polypropylene, mainly because of the mentioned kinetic reasons. These results can be used to understand the mechanism of action of the chemicals and provide valuable data for the development of the active packaging concept.

Eucalyptus Essential Oil as a Natural Food Preservative:In VivoandIn VitroAntiyeast Potential

“…In some of our previous reports [32–34], it was also observed that antimicrobial activity of essential oils was higher in vapour phase than in liquid phase, which was observed by different microscopic techniques: scanning electron microscope, transmission electron microscope, and atomic force microscope. Basically, the differences in inhibition of yeast strain obtained from essential oil (liquid phase, direct contact with the culture media) and the vapour can be attributed to the differences in diffusion coefficients of the antimicrobial compounds present in the eucalyptus oil when they have to diffuse in the agar compared to the diffusion in vapour phase [35]. In our study, the oil dose requirement was significantly reduced with the combination of the two treatments.…”

Plant antimicrobial polyphenols as potential natural food preservatives

“…At the industrial scale, there are two possible processes for including antimicrobials in packaging materials: (i) direct incorporation into the polymers during extrusion by melt‐blending and (ii) coating of the antimicrobial agents onto polymer surfaces . Extrusion is preferred by manufacturers because of the high cost of the coating process (additional steps and technical changes) .…”

Cellulose Acetate Butyrate Nanocomposites with Antimicrobial Properties for Food Packaging

“…Generally, the essential oils (EOs) possessing the strongest antibacterial properties against food‐borne pathogens contain higher concentrations of phenolic compounds such as carvacrol, eugenol, cinnamaldehyde and thymol. Linalool and methyl chavicol have also been included in different polymer structures as antimicrobial components . Their mode of action is generally considered to be the disturbance of the cytoplasmatic membrane, disrupting the proton motive force, electron flow, active transport and/or coagulation of cells content.…”