Asghar Azizian - Department of Food Hygiene and Aquatics, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Iran.
Saeid Khanzadi - Department of Food Hygiene and Aquatics, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Iran.
Mohammad Hashemi - Department of Nutrition, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
Mohammad Azizzadeh - Department of Clinical Sciences. Faculty of Veterinary Medicine. Ferdowsi University Of Mashhad, Mashhad, Iran

Introduction: This study was conducted to evaluate the influence of chitosan Nano-gel/emulsion coating functionalized by Ziziphora clinopodioides essential oil (ZCEO) and nisin on growth inhibition of Escherichia coli O157: H7 inoculated in beef samples during 16 days in cold storage condition (4˚C). Methods: Beef sample was divided into six groups after inoculation of E. coli O157:H7. Treatments including control (no coating), chitosan 2%, sonicated chitosan 2%, Nano-emulsion of chitosan coating containing ZCEO (0.5%), Nano-gel of chitosan coating containing nisin (200 IU/g), Nano-emulsion of chitosan coating containingZCEO (0.5%) and nisin (200 IU/g) were stored at refrigeration temperature and bacterial count were performed on days: 0, 1, 2, 4, 8, 12 and 16. Data were analyzed using repeated measure ANOVA and Bonferroni post hoc tests. Results: Result indicated a significant reduction in E. coli O157:H7 count in all treatments when compared to control group and the highest inhibitory activity was observed in chitosan Nano-emulsion coating containing ZCEO (0.5%) and nisin (200 IU/g). Conclusion: Accordingly, it is suggested that chitosan Nano-emulsion coating with ZCEO and nisinpractically be applied in beef to increase its safety against pathogenic bacteria especially E. coli O157: H7.

Chitosan, Functional coating, Nano technology, Beef, Escherichia coli O157:H7