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Antimicrobial effect of Essential Oils against pathogenic bacteria and optimization of its formulations combined with other preservative agents

Ghabraie, Mina (2014). Antimicrobial effect of Essential Oils against pathogenic bacteria and optimization of its formulations combined with other preservative agents Mémoire. Québec, Université du Québec, Institut National de la Recherche Scientifique, Maîtrise en microbiologie appliquée, 160 p.

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Résumé

Annually around 4 million foodborne illnesses occur in Canada resulting in an economic burden of approximately $3.7 billion. In recent years, several microbiological issues in food safety have emerged. Subsequently, novel techniques and antimicrobial formulations are required to maintain microbiologically safe foods while preserving their natural taste. Essential oils are one of the best naturally-known candidates to be used as food preservatives due to their inherent antimicrobial properties and Generally Recognised as Safe (GRAS) status. In this study, the antimicrobial activity of 32 EOs was evaluated in vitro against Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, Salmonella Typhimurium and Pseudomonas aeruginosa using 3 different methods (agar diffusion assay, micro-atmosphere assay and broth microdilution assay). Based on the results stemming from the different methods employed in this study, some EOs such as Red thyme, Red bergamot, Winter savory, Chinese cinnamon and Cinnamon bark were found to be more effective than the others as they showed higher antimicrobial activity against the tested pathogenic and spoilage bacteria. In addition, the combination effect of selected EOs was tested based on the checkerboard method. The results showed that the combination of Chinese cinnamon and Cinnamon bark EOs exhibited an additive effect against all the tested bacteria. This combination was selected to perform sensorial analyses which showed that 0.05% was the highest acceptable concentration which did not induce any negative effect on organoleptic properties of ground meat. The selected combination of EOs at 0.05% was evaluated in situ using lean ground pork against the above listed bacterial species. The results showed that this combination of EOs could effectively reduce the bacterial count in a range from 0.47 log (against L. monocytogenes) to 0.85 log (against S. aureus) after 1 day of storage while the antimicrobial efficiency decreased during the time. In another related project, multiple barrier technology (hurdle technology) was used to combine several antimicrobial factors at their sub-inhibitory concentrations for food preservation. It was deemed to be a promising way to promote antimicrobial safety without changing the natural taste and smell of food products. The antimicrobial agents were encapsulated in edible polymer to keep the activity of antimicrobial agents during the storage time. In order to find the optimized antimicrobial formulation, the combination of Chinese cinnamon and Cinnamon bark EOs was evaluated with 3 other antimicrobial agents (nitrite, nisin and organic acid salts) in situ using fresh pork sausage and fresh beef sausages.Results showed the combination of 0.025 or 0.05% of EOs with 100 ppm of nitrite, 12.5 ppm of nisin and 1.55 % of organic acid salts reduced L. monocytogenes from 1.5 to 3.6 log after 7 days of storage at 4 °C. Sensorial analyses conducted with a panel of 35 trained examiners showed that the selected formulations were organoleptically accepted in both fresh pork sausages and fresh beef sausages in terms of texture, smell and taste.

Type de document: Mémoire
Directeur de mémoire/thèse: Lacroix, Monique
Mots-clés libres: antimicrobien ; huile-essentielle ; listeria-monocytogenes ; staphylococcus-aureus ; escherichia-coli ; salmonelle-typhimurium ; pseudomonas-aeruginosa ; nitrite ; nisine ; acide-organique ; saucisse ; viande
Centre: Centre INRS-Institut Armand Frappier
Date de dépôt: 05 nov. 2015 21:18
Dernière modification: 05 nov. 2015 21:18
URI: http://espace.inrs.ca/id/eprint/2752

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