Effects of ozone treatments on microbial quality and some chemical properties of lettuce, spinach, and parsley

The effects of distilled, ozonated (12 mg L-1) and chlorinated (100 mg L-1) water treatments on inactivation of Escherichia coli and Listeria innocua inoculated on lettuce, spinach, and parsley and on some chemical characteristics (chlorophyll a, chlorophyll b, ascorbic acid, and total phenolic contents and antioxidant activity) of these vegetables were investigated. Chlorine and ozone washes resulted in average log reductions (+/- standard error) of 2.9 +/- 0.1 and 2.0 +/- 0.3 for E. coli in the vegetables tested, respectively, while the efficiency of ozone (2.2 +/- 0.1 log) was very close to that of chlorine (2.3 +/- 0.1 log) on L. innocua. Aqueous ozone did not cause any detrimental effects on the chemical characteristics of the vegetables. The effect of gaseous ozone treatment (950 mu LL-1, 20 min) on microbial inactivation and the chemical characteristics of parsley were also determined. This treatment resulted in 1.0-1.5 log reductions in the numbers of both microorganisms but caused significant losses in important bioactive compounds of parsley. Ascorbic acid and total phenolic contents and antioxidant activity in ozone-treated samples were 40.1, 14.4, and 41.0%, respectively, less than the control samples. (C) 2013 Elsevier B.V. All rights reserved.