“Intervention Strategies to Enhance the Safety of Ready-to-eat Meat Products by Plant Essential Oils

Components of plant essential oil (PEO) extracts are known to have antimicrobial properties. However, their antimicrobial efficacy in food systems is low due to their hydrophobic nature and association with other food components. Incorporation of PEO components into an appropriate carrier may offer a potential solution to improve their activity in food systems. This study was conducted to determine the effect of PEO components (thymol, eugenol, linalool, carvacrol, and cinnamaldehyde) incorporated into zein coating on inactivation of Listeria monocytogenes on a ready-to-eat meat model, frankfurters (hot dogs). Hot dogs were inoculated with 7 log CFU/sample and dipped into prepared PEO-zein coatings. Samples were vacuum packaged and stored at 10ºC for 9 days or 4ºC for 4 weeks. Survival of L. monocytogenes was investigated by direct plating onto modified Oxford agar. Enrichment using UVM broth and Fraser broth was conducted when the pathogen was not detected by direct plating. Generally, results show that the PEO loaded coatings are effective against L. monocytogenes at 10 and 4ºC. When compared to the coating control (zein coating without PEO) at 10ºC, coatings loaded with 10% cinnamaldehyde and 1% carvacrol showed the greatest inhibitory effect and suppressed growth of L. monocytogenes by 2.4 and 2.1 log CFU/sample, respectively, after 9 days of storage. At 4ºC, the coating loaded with carvacrol was most effective at suppressing growth of L. monocytogenes (1.54-log reduction). No or little dose-response association between PEO concentration and antimicrobial activity was observed in the study. While further research is still required, this study indicates that incorporation of PEOs in corn zein to be used as an edible coating has a high potential to enhance the safety in ready-to-eat meat.