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The objectives of this study are to examine the effects of ozone (03) on the pathogen Listeria monocytogenes. Ozone is one of the most powerful oxidizing agents (52% stronger than chlorine) and is effective against a broad spectrum of microorganisms, including viruses, bacteria, yeast and molds.
Ozone has recently been recommended for approval as Generally Recognized As Safe (GRAS) in food production. Little or no research has been performed on the influence that ozone has on the destruction of L. monocytogenes. This proposal will determine important parameters of ozone-induced injury and death of L. monocytogenes. The optimal conditions of ozone exposure for listerial death will be determined. Initial variables will include time, temperature and ozone concentration. Injury and death will be determined using a dual plating procedure, and by the release of subcellular components. The thermodynamics of ozone inactivation will be determined. Any differences in the phase of growth on the susceptibility of L. monocytogenes to ozone will be examined.Recovery of ozone-injured listerial cells will be studied, as will be the site(s) of ozone damage. The influence of ozone in reducing listerial counts in a food product (cabbage) will also be determined. The influence of ozone on the enzymes catalase and superoxide dismutase in L. monocytogenes will be examined immediately following exposure and during recovery .