Effect of Ozone Treatment on Inactivation of Escherichia coli and Listeria sp. on Spinach

Shreya Wani, Jagpreet K. Maker, Joseph R. Thompson, Jeremy Barnes and Ian Singleton
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Shreya Wani: School of Biology, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
Jagpreet K. Maker: School of Biology, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
Joseph R. Thompson: School of Biology, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
Jeremy Barnes: School of Biology, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
Ian Singleton: School of Biology, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK

Agriculture, 2015, vol. 5, issue 2, 1-15

Abstract: The efficacy of “gaseous” ozone in reducing numbers and re-growth of food-borne pathogens, ( Escherichia coli and Listeria spp.), on leafy salads was investigated using spinach. A preliminary in vivo study showed 1-log reduction in six strains of E. coli and two species of Listeria spp. on spinach exposed to 1 ppm ozone for 10 min. A range of ozone treatments were explored to deliver optimal bacterial inactivation while maintaining the visual appearance (color) of produce. Exposure to a higher ozone concentration for a shorter duration (10 ppm for 2 min) significantly reduced E. coli and Listeria spp. viable counts by 1-log and the pathogens did not re-grow following treatment (over a nine-day storage period). Impacts of 1 and 10 ppm ozone treatments were not significantly different. Approximately 10% of the pathogen population was resistant to ozone treatment. We hypothesized that cell age may be one of several factors responsible for variation in ozone resistance. E. coli cells from older colonies demonstrated higher ozone resistance in subsequent experiments. Overall, we speculate that gaseous ozone treatment constitutes the basis for an alternative customer-friendly method to reduce food pathogen contamination of leafy produce and is worth exploring on a pilot-scale in an industrial setting.

Keywords: gaseous ozone; E. coli; Listeria spp. (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2015
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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