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Active edible coating and gamma-irradiation as cold combined treatments to assure the safety of broccoli florets (Brassica oleracea L.)

Ben-Fadhel, Yosra; Saltaji, Sabrina; Khlifi, M.A.; Salmieri, Stéphane; Vu, Khanh Dang; Lacroix, Monique (2017). Active edible coating and gamma-irradiation as cold combined treatments to assure the safety of broccoli florets (Brassica oleracea L.) International Journal of Food Microbiology , vol. 241 . p. 30-38. DOI: 10.1016/j.ijfoodmicro.2016.10.010.

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Résumé

The antimicrobial activity of essential oils (EOs), organic acid (OA) salts and natamycin, a natural antifungal produced during fermentation by the bacterium Streptomyces natalensis, was assessed against four pathogens (Escherichia coli O157:H7, Listeria monocytogenes, Salmonella Typhimurium and Aspergillus niger). The Minimum Inhibitory Concentration (MIC) of each antimicrobial (AM) was assessed to determine their efficiency on tested microbial species in order to select the most efficient. Then, the interactions between different antimicrobial compounds showing the lowest MIC were determined by the checkerboard method. The most effective antimicrobial formulation showing synergittic or additive effects was then encapsulated in an alginate matrix to protect the antimicrobial efficiency during storage. The effectiveness of the formulation was then evaluated in situ using broccoli as a food model. A combined treatment of active coating and gamma-irradiation (0.4 and 0.8 kGy) was also done in order to evaluate the possible synergistic effect between treatments. The results of this study allowed the selection of 4 EOs, one OA salt and the natamycin as an antifungal agent exhibiting lower MIC values. The interactive antimicrobial effects between them showed that an antimicrobial formulation composed of 300 ppm of lemongrass EO, 5000 ppm of sodium diacetate and 80 ppm of natamycin resulted in an additive effect against A. niger, E. coli and S. Typhimurium and showing synergistic effect against L. monocytogenes. Finally, in situ analyses showed a synergistic antimicrobial activity between active coating and gamma-irradiation and allowed the extension of the shelf-life of ready-to-eat (RTE) broccoli during storage at 4 degrees C. (C) 2016 Elsevier B.V. All rights reserved.

Type de document: Article
Mots-clés libres: Active coating; Natural antimicrobial compounds; Shelf-life; Spoilage bacteria; Synergy; γ-Irradiation
Centre: Centre INRS-Institut Armand Frappier
Date de dépôt: 05 oct. 2017 21:04
Dernière modification: 05 oct. 2017 21:04
URI: http://espace.inrs.ca/id/eprint/5324

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