title: Slicing under chlorinated water improves the disinfection of fresh-cut romaine lettuce.
abstract: The aim of this study was to determine whether the timing or mode of application influences the antimicrobial efficacy of a sodium hypochlorite solution against microorganisms on fresh-cut Romaine lettuce. Lettuce leaves were treated with a solution of sodium hypochlorite containing  70 mg liter(-1) free chlorine prior to slicing (WLS), while submerged in the solution (CWS), or after slicing (PCS), the last being common practice in the fresh-cut industry. Immediate antimicrobial effects were determined from analyses performed directly after treatment, while  delayed effects were derived from analysis of packaged samples stored at 4 and 15°C. Experiments were performed with both uninoculated and inoculated whole leaves, using Escherichia coli O157:H7 from a type collection as an inoculum. The CWS treatment provided the greatest initial  reductions in aerobic plate counts of E. coli O157:H7 populations, followed by PCS and WLS. The advantage afforded by the CWS approach was maintained over 10 days in storage at 4°C. In addition, it was noted that the visual quality attributes of the fresh-cut lettuce from the CWS  approach were better than those from the other two treatments. These results collectively suggest that slicing lettuce under a sanitizer solution could provide better disinfection of fresh-cut Romaine lettuce than the current practice of washing with sanitizer after cutting has taken place.
authors.affiliation: Agriculture and Agri-Food Canada, Pacific Agri-Food Research Centre, 4200 Highway 97, Summerland, British Columbia, Canada V0H 1Z0. peter.toivonen@agr.gc.ca
authors.forename: Peter M A
authors.initials: PM
authors.lastname: Toivonen
authors.forename: Changwen
authors.initials: C
authors.lastname: Lu
authors.forename: Pascal
authors.initials: P
authors.lastname: Delaquis
authors.forename: Susan
authors.initials: S
authors.lastname: Bach
mesh_terms: D015169:Colony Count, Microbial; D004202:Disinfectants / Q000494:pharmacology*; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000254:growth & development; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control; D005511:Food Handling / Q000379:methods*; D018857:Food Packaging; D005519:Food Preservation; D059022:Food Safety; D006801:Humans; D018545:Lactuca / Q000382:microbiology*; D012973:Sodium Hypochlorite / Q000494:pharmacology*; D013696:Temperature
chemical_list: D004202:Disinfectants; D012973:Sodium Hypochlorite