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with those of standard PP films. Antimicrobial tests were carried out for enterobacteria, total 20 aerobic counts, yeasts and moulds, and lactic acid bacteria and psychrotrophic bacteria, and the 21 effect of the release of the antimicrobial agent on the sensory characteristics of the salads was 22 also studied. The application of the EVOH coating results in an increase in the tensile resistance 23 of the PP films and a reduction in the elongation at break. The results showed that 24 microorganism counts bacteria decreased especially at the beginning of the storage period. OEO 25 and CITRAL samples had reductions of 1.38 log and 2.13 log respectively against 26 enterobacterias, about 2 log against yeasts and moulds. The total aerobic counts reduced 1.08 27 log with OEO and 1.23 log with CITRAL and the reduction of lactic acid bacteria and 28 psychrotrophic was about 2 log.. Citral-based films appeared to be more effective than materials 29 containing oregano essential oil in reducing spoilage flora during storage time. Sensory studies 30 also showed that the package with citral was the most accepted by customers at the end of the 31 shelf life 32 33 Keywords: minimally processed salads, citral, oregano essential oil, antimicrobial packaging, 34 mechanical properties, EVOH.

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This study aims to develop antimicrobial films consisting of chitosan and silver nanoparticles that are homogeneously distributed throughout the polymer matrix. Nanoparticles were generated in situ during the neutralization of the chitosan acetate film with sodium hydroxide. The temperature of neutralization and the concentration of silver in the film were crucial determinants of the shape and size of the nanoparticles. Neutralized films exhibited antimicrobial activity against Escherichia coli and Staphylococcus aureus in liquid growth media. However, the effectiveness of the films was considerably greater in diluted growth media. Furthermore, no significant differences were found either in the antimicrobial capacities of films incorporating different amounts of silver or in the amount of silver that migrated into the liquid media after 18 h of immersion of the film. Neutralized films maintained their activity after 1 month of immersion in deionized water, which can be attributed to the slow sustained release of silver ions and thus efficacy over time.