Efficacy of natural antimicrobial systems used in foods; bacterial stress response and mode of action.

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According to the Canadian Food Inspection Agency, there are 11 million cases of food borne illnesses every year. Ground beef contaminated with Escherichia coli O157:H7 made the news headlines in the fall of 2012. Furthermore, meat and meat products remain the type of foods most often associated with food borne illnesses. Consumer demands for convenient, minimally processed, safer foods with extended shelf life have been a driving force in the development of new strategies to improve food microbial quality and safety. Natural antimicrobials, such as polyphenolic compounds extracted from plants have been successfully studied in our laboratory for that purpose both in animal feed (oregano oil and cranberry pulpe) and in processed meat formulations (thyme essential oil) during challenge and shelf life studies. Beyond cell enumeration and log reductions, we must understand the mechanism of action and resistance associated with these new natural antimicrobials at the molecular level. Hence, using PCR analysis and microarray technology, gene expression in target cells (Escherichia coli, Listeria monocytogenes, Clostridium, etc.) will be studied upon exposition to natural antimicrobial notably essential oil of thyme onion extract, nisin, etc. This molecular analysis will allow a more effective selection of antimicrobial combination of treatments. In the long run, having the plant and animal production sectors involved together in reducing waste and spoilage while improving food safety, is a more sustainable approach for our agri-food sector. This will have a positive impact on its socio-economic growth, and on public health through the reduction of food borne outbreaks.