A comparison of ozone and chlorine to reduce the microbial load in fresh lettuce

TL;DRAbstract

The effects of ozone were examined on fresh head lettuce as a means for reducing the initial microbial load (about 10^4-10^5 CFU/g) on the lettuce. Ozone concentrations used were 50 parts per million and 100 ppm. These concentrations resulted in an average reduction ofboth mesophilic and psychrotrophic bacteria of 2.04 and 2.57 log_10 CFU/g on the initial load of microorganisms on the lettuce. Once the effect was established, ozone was compared to a sodium hypocholorite treatment, which is a method currently used in industry. The concentrations used for comparison of ozone and chlorine were 1 mM and 2 mM for each. The reactions were stopped in both cases by using sodium thiosulfate (Na2S2O3) to determine the initial effect of both ozone and chlorine. By using a neutralizer, the effects due to residual ozone or chlorine on the lettuce were eliminated. At 1 mM, ozone resulted in an average inactivation of mesophilic and psychrotrophic bacteria of 1.15 log_10 CFU/g and at 2 mM, an average

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