title: Inactivation of stressed Escherichia coli O157:H7 cells on the surfaces of rocket salad leaves by chlorine and peroxyacetic acid.
abstract: Because Escherichia coli O157:H7 has been frequently associated with many foodborne outbreaks caused by consumption of leafy greens (lettuce, spinach, and celery), this study investigated the ability of deionized water, chlorine, and peroxyacetic acid to detach or inactivate stressed and unstressed cells of E. coli O157:H7 contaminating the surfaces of rocket salad leaves. E. coli O157:H7 cells stressed by acid, cold, starvation, or NaCl exposure, as well as unstressed cells, were inoculated on the surfaces of rocket salad leaves at 4°C. The effectiveness of two sanitizers (200 ppm of chlorine and 80 ppm of peroxyacetic acid) and deionized water for decontaminating the leaves treated with stressed and unstressed E. coli O157:H7 were evaluated during storage at 10 or 25°C for 0.5, 1, 3, and 7 days. It was found that washing with 80 ppm of peroxyacetic acid was more effective and reduced unstressed and stressed cells of E. coli O157:H7 by about 1 log CFU per leaf on the leaves. There was no apparent difference in the ability of stressed and unstressed cells to survive surface disinfection with the tested agents. Treatments to reduce viable E. coli O157:H7 cells on rocket leaves stored at 25°C were more effective than when used on those stored at 10°C. Washing with peroxyacetic acid or chlorine solution did not ensure the safety of rocket leaves, but such treatments could reduce the likelihood of water-mediated transfer of E. coli O157:H7 during washing and subsequent processing.
authors.affiliation: Department of Nutrition and Food Technology, Jordan University of Science and Technology, Irbid 22110, Jordan.
authors.forename: Anas A
authors.initials: AA
authors.lastname: Al-Nabulsi
authors.affiliation: Department of Nutrition and Food Technology, Jordan University of Science and Technology, Irbid 22110, Jordan.
authors.forename: Tareq M
authors.initials: TM
authors.lastname: Osaili
authors.affiliation: Department of Nutrition and Food Technology, Jordan University of Science and Technology, Irbid 22110, Jordan.
authors.forename: Heba M
authors.initials: HM
authors.lastname: Obaidat
authors.affiliation: Department of Nutrition and Food Technology, Jordan University of Science and Technology, Irbid 22110, Jordan.
authors.forename: Reyad R
authors.initials: RR
authors.lastname: Shaker
authors.affiliation: Department of Nutrition and Food Technology, Al-Balqa Applied University, Al-Salt 19117, Jordan.
authors.forename: Saddam S
authors.initials: SS
authors.lastname: Awaisheh
authors.affiliation: Department of Food Science, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Holley
mesh_terms: D002713:Chlorine / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004202:Disinfectants / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000254:growth & development; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D006801:Humans; D018545:Lactuca / Q000382:microbiology; D010463:Peracetic Acid / Q000494:pharmacology*; D018724:Spinacia oleracea / Q000382:microbiology; D013696:Temperature; D013997:Time Factors; D014675:Vegetables / Q000382:microbiology*
chemical_list: D004202:Disinfectants; D002713:Chlorine; D010463:Peracetic Acid