Survival of Escherichia coli O157:H7 in Ground Beef after Sublethal Heat Shock and Subsequent Isothermal Cooking
Abstract:Heat shock of Escherichia coli O157:H7 in broth media reportedly leads to enhanced survival during subsequent heating in broth medium or ground beef. Survival of E. coli O157:H7 during slow cooking thus may be enhanced by prior exposure to sublethal heat shock conditions, thereby jeopardizing the safety of slow-cooked products such as beef roasts. This study examined the effect of heat shocking E. coli O157:H7–inoculated lean (6 to 9% fat) ground beef on the survival of the pathogen in the same ground beef during a subsequent 4-h, 54.4°C cooking process. Six different combinations of heat shock temperature (47.2, 48.3, or 49.4°C) and time (5 or 30 min) were applied to a five-strain cocktail of microaerophilically grown cells in 25 g of prewarmed ground beef, which was followed by cooking at 54.4°C. Temperature during a 30-min heat shock treatment did not significantly affect E. coli O157:H7 survival during subsequent isothermal cooking (P > 0.05). Survival after a 5-min heat shock was higher when the heat shock temperature was 48.3 or 49.4°C (P < 0.05) than when it was 47.2°C. The D-values at 54.4°C (130°F) (D 54.4-value) of the process significantly increased only when cells were exposed to a heat shock combination of 5 min at 49.4°C. Mean (n = 3 trials) reductions in E. coli O157:H7 during the 4-h, 54.4°C isothermal cooking process ranged from 4.3 to 7.5 log CFU/g. Heating E. coli O157:H7–contaminated beef at the high end of the sublethal temperature range for 5 min could increase survival of E. coli O157:H7 during subsequent slow-cooking processes.
Document Type: Research Article
Affiliations: 1: Department of Food Science, University of Wisconsin–Madison, 1605 Linden Drive, Madison, Wisconsin 53706, USA 2: Division of Food Safety, Wisconsin Department of Agriculture, Trade and Consumer Protection, P.O. Box 8911, Madison, Wisconsin 53708, USA
Publication date: August 1, 2009
- IAFP Members with personal subscriptions to JFP Online: To access full-text JFP or JMFT articles, you must sign-in in the upper-right corner using your Ingenta sign-in details (your IAFP Member Login does not apply to this website). The Journal of Food Protection (JFP) is a refereed monthly publication. Each issue contains scientific research and authoritative review articles reporting on a variety of topics in food science pertaining to food safety and quality. The Journal is internationally recognized as the leading publication in the field of food microbiology with a readership exceeding 11,000 scientists from 70 countries. The Journal of Food Protection is indexed in Index Medicus, Current Contents, BIOSIS, PubMed, Medline, and many others.
Print and online subscriptions are available to IAFP Members and institutional subscribers. IAFP Members with a subscription to JFP Online will have access to all available JFP and JMFT content. Online visitors who are not IAFP Members or journal subscribers will be charged on a pay-per-view basis. Membership and subscription information is available at www.foodprotection.org.
- Information for Authors
- Submit a Paper
- Subscribe to this Title
- Membership Information
- Information for Advertisers
- Ingenta Connect is not responsible for the content or availability of external websites