Fate of natural bacterial flora, and artificially inoculated Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica in raw ground chicken meat with added oregano oil or tannic acid alone or combined

Abstract

The antibacterial effect of oregano oil and tannic acid (TA) on the aerobic plate count (APC), Enterobacteriaceae (ENT), Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica in raw ground chicken breast meat (RGCBM) held at 4 °C and 10 °C was studied. Five treatments including i) control (no antimicrobial), ii) 200 ppm oregano oil, iii) 10 ppm TA, iv) 200 ppm oregano oil + 10 ppm TA, and v) 5 ppm butylated hydroxy anisole (BHA) were prepared. Oregano oil, TA, and BHA inhibited increases in the APC when used separately (P < 0.05). Oregano oil + TA exhibited a higher (P < 0.05) antibacterial effect on APC during storage of RGCBM at 4 °C and 10 °C. Also, that same combination significantly (P < 0.05) inhibited growth of E. coli O157:H7, L. monocytogenes, S. enterica, and ENT in the meat irrespective of storage temperature. However, from a practical perspective, pathogen inhibition is unlikely to be deemed effective. Based on these results, the antibacterial activity of oregano oil is improved by TA, and the oregano oil + TA combination has good potential for controlling growth of native bacterial flora to enhance the microbial shelf-life of RGCBM.