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Utilization of Ozone for the Decontamination of Small Fruits
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org
Citation: Paper number 056147, 2005 ASAE Annual Meeting . @2005
Authors: Katherine L. Bialka, Ali Demirci
Keywords: E. coli O157:H7, Salmonella, strawberry, gaseous ozone
Each year there are approximately 76 million foodborne illnesses and fresh produce is the
second most common vehicle for such illnesses. Small fruits have been implicated in several
outbreaks although none have been bacterial. Prior to market small fruits are not washed or treated
in any manner so as to extend their shelf life. Washing alone is not a viable option and the use of
novel technologies needs to be investigated. One such technology is ozone which has been used to
treat drinking water since the late nineteenth century. The efficacy of gaseous ozone to
decontaminate pathogens on strawberries, which were used as a model for small fruits, was
investigated in this study. Strawberries were artificially contaminated with 5 strains of E. coli
O157:H7 and Salmonella. Fruits were treated with 4 ozone treatments; i) continuous ozone flow for
2, 4, 8, 16, 32, and 64 min, ii) pressurized ozone (83 kPa) for 2, 4, 8, 16, 32, and 64 min, iii)
continuous ozone (64 min) followed by pressurized ozone (64 min). Maximum reductions of 1.81,
2.32, and 2.96 log10 CFU/g of E. coli O157:H7 were achieved for continuous, pressurized, and
continuous followed by pressurized ozone, respectively. For Salmonella reductions of 0.97, 2.18,
and 2.60 log10 CFU/g were achieved for continuous, pressurized, and continuous followed by
pressurized ozone, respectively. It was concluded that continuous ozone was the least effective
treatment, and that there was no significant difference between pressurized ozone treatment and
continuous followed by pressurized ozone treatment. These results demonstrate that gaseous
ozone has the potential to be used a decontamination method for small fruits.
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