Ozone Use As an Antimicrobial Agent On Broccoli Sprouts Inoculated with Escherichia Coli

Ozone use as an antimicrobial agent on broccoli sprouts inoculated with Escherichia coli

Session 85 (85-7),Quality Assurance, 1:30 PM – 3:30 PM, 2001-06-26 Room 265 , 2001 IFT Annual Meeting – New Orleans, Louisiana , C. E. BEYER and B. C. Hampson. Food Science and Nutrition Department, California Polytechnic State University, San Luis Obispo, CA 93407


Sprouts are a public health concern due to the potential for pathogen growth during sprout production and subsequent transmission to consumers. Lately, there have been a number of foodborne outbreaks associated with sprout consumption. Currently, the FDA recommends the use of an approved seed disinfection treatment of 20,000 ppm calcium hypochlorite solution. Alternative treatments may be used if a >3.5 log-fold reduction in CFU’s is achieved and complies with EPA and FDA requirements. The FDA recommends testing spent irrigation water after 48 hours of growth. According to the FDA, the test indicates levels of pathogens on the sprouts at about 1 log more than found in the water. The objective of this study was to determine if the use of ozone-enriched irrigation water caused a reduction in E. colithat was inoculated onto broccoli sprout seeds and subsequently grown to harvest. Wild-type E. coli at a concentration of 101 to 103 CFU/ml was inoculated (1 hour for adhesion) onto sprout seeds. The seeds were next steeped for 2 hours in 4 ppm ozone-enriched water at ambient temperature. Sprouts were irrigated with this 4 ppm ozone solution twice daily during their growth period. Irrigation water was tested for a reduction in E. coli after 48 hours and sprouts were analyzed after 6 days of growth Results indicate a one log-fold reduction in CFU/ml of E. coli. Thus, use of ozone alone did not lead to a 3.5 log reduction of inoculated E. coli. Further investigation is needed to demonstrate ozone’s effectiveness in conjunction with other disinfectants for the reduction of pathogenic bacteria on sprouts. Furthermore, spent irrigation water showed significantly more than a 1 log difference in the amount of E. coli present on the sprouts. In these experiments, E. coli consistently increased in number as the sprouts grew-out.