17D-17 |
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I. C. BLACKMAN1, Y. W. Park1, and M. A. Harrison2. (1) Agricultural Research Station, Fort Valley State Univ., 1005 State University Dr., Fort Valley, GA 31030-4313, (2) Dept. of Food Science & Technology, Univ. of Georgia, 340 Food Science Bldg., Athens, GA 30602-7610 The water activity of venison jerky and the pH and processing temperature of dry cured salami should limit survival of pathogens like Escherichia coli O157:H7 in those products. However, illness outbreaks related to these foods by this pathogen showed its potential tolerance to environmental stresses. In the global stress response in bacteria, oxidative stress confers cross protection to thermal stress. A chemical complex containing iron III chloride, ADP and ascorbic acid in the molar concentration of 1:1:4, respectively, elicits oxidative stress in fibroblasts. These compounds are in processed meats and may elicit oxidative stress on the bacterium, thus conferring thermotolerance. The objective was to determine the effect of oxidative compounds on the thermotolerance of E. coli O157:H7 strains 380-94 and EO139. Cultures of E. coli O157:H7 strain 380-94 were mixed with three different concentrations (10:10:40, 15:15:60 and 20:20:80) of the oxidative complex (iron III chloride, ADP and ascorbic acid). The mixtures were then subjected to a temperature of 60oC for up to 1 hour using the capillary tube method. Strain 380-94 was chosen for this study because of its heat resistance. The formulation enhancing the thermotolerance of 380-94 was then used to determine its influence on the thermotolerance of EO139. The thermotolerance of E. coli O157:H7 strains EO139 and 380-94 was influenced by the concentration of the oxidative complex. The ratio of 10:10:40 enhanced thermotolerance at 59 and 60oC of EO139 and 390-94, respectively. Ratios of 15:15:60 and 20:20:80 reduced populations and did not enhance the thermotolerance of the cells. Enhancement of thermotolerance of E. coli O157:H7 by the oxidative complex is concentration, time and temperature dependent. These chemicals present in meats provide potential survival factors. Proper heating or dehydrating meat at 60oC for a sufficient time may be necessary to curb the thermotolerance of the pathogen.
Session 17D, Food Chemistry: Chemical effects of food processing and preservation
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