title: Sanitation and design of lettuce coring knives for minimizing Escherichia coli O157:H7 contamination.
abstract: This study was undertaken to examine the effect of ultrasound in combination with chlorine on the reduction of Escherichia coli O157:H7 populations on lettuce coring knives. Two new coring devices designed to mitigate pathogen attachment were fabricated and evaluated. The coring rings of the knives were dip inoculated with soil slurry containing 10⁶ E. coli cells and treated with chlorinated water with and without ultrasonication for 30, 60, and 120 s. The rough welding joints on currently used in-field lettuce coring knives provided a site conducive to bacterial attachment and resistant to cell removal during sanitation treatment. The two modified coring knives harbored significantly fewer E. coli cells than did the currently used commercial model, and the efficacy of the disinfection treatment was high (P < 0.05). Ultrasound treatment reduced the E. coli O157:H7 counts to below the detection limit of 1.10 log CFU/cm² at both the coring ring blade and welding joint within 30 s in 1 ppm of chlorinated water. The redesigned coring knives and an ultrasound plus chlorine combination treatment may provide practical options for minimizing the microbial safety hazards of lettuce processed by core-in-field operations.
authors.affiliation: Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhou
authors.forename: Yaguang
authors.initials: Y
authors.lastname: Luo
authors.forename: Patricia
authors.initials: P
authors.lastname: Millner
authors.forename: Hao
authors.initials: H
authors.lastname: Feng
mesh_terms: D001422:Bacterial Adhesion; D002713:Chlorine / Q000494:pharmacology; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D003297:Cooking and Eating Utensils; D019453:Escherichia coli O157 / Q000254:growth & development / Q000502:physiology*; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control*; D006801:Humans; D018545:Lactuca / Q000382:microbiology*; D014465:Ultrasonics
chemical_list: D002713:Chlorine