Effect of alginate coatings containing Zataria Multiflora Boiss essential oil in forms of coarse emulsion and Nano-emulsion on inoculated Escherichia coli O157:H7 in beef fillets

Abstract

The present study aimed to compare the inhibitory effects of alginate coatings containing Zataria multiflora Boiss essential oil (ZMEO) in the forms of coarse emulsion and nano-emulsion on the growth of inoculated Escherichia coliO157: H7in beef fillet during 16 days of refrigeration at the temperature of 4 . Alginate solutions (3%) with various concentrations of ZMEO (0.25%, 0.5%, and 1%) were prepared, and the coarse emulsion and nano-emulsion forms were also prepared. The beef fillets were inoculated with E. coliO157: H7(1.5×105 log CFU/g) and immersed in various alginate treatments, and the bacterial count was performed during refrigeration on days zero, four, eight, 12, and 16.The obtained results indicated that the alginate coating containing ZMEO in both forms (coarse/nano-emulsion) was a proper candidate to control E. coliO157: H7at the temperature of 4°C. However, the antibacterial effects were more significant on the samples treated by the nano-emulsion form compared to the coarse emulsion form and controls. In addition, the lowest bacterial growth was observed in the samples coated with the alginate nano-emulsion containing 1% ZMEO (5.3±0.24 log CFU/g) at the end of storage. Therefore, it could be concluded that the use of alginate coatings containing ZMEO (particularly in the nano-emulsion form) could effectively decrease the growth of E. coliO157: H7 during storage, and this natural additive could be applied in the food industry, especially the meat industry.