SENSITIVITY OF LISTERIA MONOCYTOGENES TO SPICES AT TWO TEMPERATURES

Abstract

ABSTRACT Thirteen spices were screened for growth inhibition effect against Listeria monocytogenes at 24°C using a concentration gradient plate method. Cloves, and oregano were the two most inhibitory spices with MIC values ranging from 0.5 to 0.7% (W/V). Inhibition was also detected with sage and rosemary (MIC of 0.7 to 1.0%) as well as nutmeg (MIC of 1.1–1.4%). Black pepper, chili, cinnamon, garlic, mustard, paprika, parsley and red pepper at a concentration up to 3.0% did not inhibit the growth of the organisms. The effect of cloves, oregano and sage on the growth and survival of L. monocytogenes Scott A was further tested in tryptic soy broth at both 4 and 24°C. At a concentration of 0.5 or 1.0%, cloves were bactericidal and oregano was bacteriostatic to this organism at both incubation temperatures. Sage at these two concentrations was bactericidal at 4°C and bacteriostatic at 24°C. When tested in sterile meat slurry, a 1.0% level of either cloves or oregano had little effect on the growth of L. monocytogenes Scott A at 4 or 24°C.