title: Combined effects of mustard flour, acetic acid, and salt against Esherichia coil O157:H7 stored at 5 and 22 degrees C.
abstract: The combined effects of acetic acid and mustard flour were investigated to ascertain their impact on Escherichia coli O157:H7 stored at 5 and 22 degrees C. Samples were prepared with various concentrations of acetic acid (0, 0.25, 0.5, 0.75, and 1% [vol/vol]) combined with 10% (wt/vol) Baltimore or Coleman mustard flour and 2% (fixed; wt/vol) sodium chloride. An acid-adapted mixture of three E. coli O157:H7 strains (10(6) to 10(7) CFU/ml) was inoculated into prepared mustard samples that were stored at 5 and 22 degrees C, and samples were assayed periodically for the survival of E. coli O157:H7. The numbers of E. coli O157:H7 were reduced much more rapidly at 22 degrees C than at 5 degrees C. E. coli O157:H7 was rapidly reduced to below the detection limit (<0.3 log10, CFU/ml) after 1 day at 22 degrees C, whereas it survived for up to 5 days at 5 degrees C. There was no synergistic or additive effect with regard to the killing of E. coli O157:H7 with the addition of small amounts of acetic acid to the mustard flour. When stored at 5 degrees C, mustard in combination with 0.25 (M-0.25), 0.5 (M-0.5), and 0.75% (M-0.75) acetic acid exerted less antimicrobial activity than the control (M-0). The order of lethality at 5 degrees C was generally M-0.25 = M-0.5 < M-0.75 = M-0 < M-1. The addition of small amounts of acetic acid (<0.75%) to mustard retards the reduction of E coli O157:H7. Statistical reduction in populations of E. coli O157:H7 (P < 0.05) was enhanced relative to that of the control (mustard alone) only with the addition of 1% acetic acid. This information may help mustard manufacturers to understand the antimicrobial activity associated with use of mustard flour in combination with acetic acid.
authors.affiliation: Department of Food Science and Human Nutrition, Washington State University, Pullman 99164-6376, USA.
authors.forename: Min-Suk
authors.initials: MS
authors.lastname: Rhee
authors.forename: Richard H
authors.initials: RH
authors.lastname: Dougherty
authors.forename: Dong-Hyun
authors.initials: DH
authors.lastname: Kang
mesh_terms: D019342:Acetic Acid / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004305:Dose-Response Relationship, Drug; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000254:growth & development; D005433:Flour; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D009149:Mustard Plant; D012965:Sodium Chloride / Q000494:pharmacology*; D013696:Temperature
chemical_list: D012965:Sodium Chloride; D019342:Acetic Acid