Inactivation of Cronobacter by gaseous ozone in milk powders with different fat contents

The inactivation of Cronobacter by gaseous ozone treatments was studied in whole milk powder (WMP) and skimmed-milk powder (SMP). Samples inoculated at 5.92 log cfu g−1 were exposed to a continuous stream of constant ozone concentrations of 2.8 and 5.3 mg L−1 for up to 120 min. Initial levels of Cronobacter in SMP were reduced by 2.71 and 3.28 log after 120 min of ozonation at 2.8 and 5.3 mg L−1, respectively. Counts were reduced by 1 log less in WMP after the same exposure period. The thiobarbituric acid reactive substances (TBARS) assay was used to monitor oxidation in milk powder samples and indicated that no significant (P > 0.05) changes occurred in the level of oxidation of WMP and SMP during ozonation at both ozone concentrations. Gaseous ozone treatment was found to be a promising method for the reduction of Cronobacter especially in SMP.