title: Inactivation of Escherichia coli O157:H7 in packaged ground beef by allyl isothiocyanate.
abstract: Commercial allyl isothiocyanate (AIT) was examined for its ability to reduce numbers of Escherichia coli O157:H7 inoculated in fresh ground beef packaged under nitrogen and stored refrigerated or frozen. A five-strain cocktail of E. coli O157:H7 containing 3 or 6 log10 cfu/g was inoculated into 100 g ground beef and formed into 10x1-cm patties. A 10-cm diameter filter paper disk treated with AIT suspended in sterile corn oil was placed on top of a single patty. One patty and paper disk were placed in a bag of Nylon/EVOH/PE with O2 permeability of 2.3 cm3 m(-2) 24 h atm at 23 degrees C. The bags were back-flushed with 100% nitrogen, heat-sealed and stored at 10, 4 and -18 degrees C for 8, 21 or 35 days, respectively. During storage, the AIT levels in the package headspaces were determined by gas liquid chromatography, and mesophilic bacteria and E. coli O157:H7 were counted. The mesophilic aerobic bacteria in ground beef patties were largely unaffected by the addition of AIT. At an initial population of 3 log10 cfu/g, E. coli O157:H7 was reduced by AIT to undetectable levels after 18 days at 4 degrees C or 10 days at -18 degrees C. In samples inoculated with 6 log10 cfu/g, a >3 log10 reduction of E. coli O157:H7 was observed after 21 days at 4 degrees C, while a 1 log10 reduction was observed after 8 and 35 days at 10 and -18 degrees C, respectively. The final AIT concentrations in the headspaces after storage at 10, 4, and -18 degrees C were 444, 456, and 112 microg/ml at 8, 21, and 35 days, respectively. Results showed that AIT can substantially reduce numbers of E. coli O157:H7 in fresh ground beef during refrigerated or frozen storage.
authors.affiliation: Department of Food Science, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada.
authors.forename: D
authors.initials: D
authors.lastname: Nadarajah
authors.forename: J H
authors.initials: JH
authors.lastname: Han
authors.forename: R A
authors.initials: RA
authors.lastname: Holley
mesh_terms: D000818:Animals; D002417:Cattle; D015169:Colony Count, Microbial; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000254:growth & development; D005516:Food Microbiology; D018857:Food Packaging / Q000379:methods*; D005519:Food Preservation / Q000379:methods; D005520:Food Preservatives / Q000032:analysis / Q000494:pharmacology*; D006801:Humans; D017879:Isothiocyanates / Q000032:analysis / Q000494:pharmacology*; D008461:Meat Products / Q000382:microbiology*; D013696:Temperature; D013997:Time Factors; D014618:Vacuum
chemical_list: D005520:Food Preservatives; D017879:Isothiocyanates; C004471:allyl isothiocyanate