100A-14 |
D and Z values of Salmonella agona as influenced by media composition |
S. A. Ibrahim1, T. A. LLOYD1, M. M. Salameh2, C. W. Seo1, R. Purcell1, and G. Shahbazi2. (1) Food Science and Nutrition, North Carolina Agricultural and Technical State University, 171-B Carver Hall, Food Microbiology lab, Greensboro, NC 27411-1064, (2) Food Bioprocess Engineering, North Carolina Agricultural and Technical State University There has been a dramatic rise in the incidence of salmonellosis all over the world, including the United States. In the US alone, there are an estimated 2-4 million cases annually, resulting in more than 500 deaths per year. A recent multi-state outbreak of Salmonella agona (S.agona ) received press attention because it was the first outbreak of Salmonella in a commercial cereal product. Little information is available about the thermal resistance of this foodborne pathogen. The purpose of this work was to determine the D and Z values of S. agona as influenced by media composition. Two strains, H 6115 and F 5567, were obtained from the Center for Disease Control (CDC). The thermal behavior of S. agona to achieve at least 5-log CFU was determined. The D and Z values under different media composition were also calculated. Heat treatment at 55oC for 20 min, 57.5oC for 14, min and 60oC C for 5 min were needed to achieve a 5-log reduction in microbial populations. The addition of 3% sodium acetate or 3% sodium chloride showed significant reduction in microbial populations. The calculated D and Z values were also decreased significantly (P < 0.05) in the presence of sodium acetate or sodium chloride. In a model broth system, thermal death time at 57.5 oC C was reduced by up to 1.5-log after microbial cells were treated with Tween 20, or bifidogenic factor. Cold shock at 2oC C for 30 min, prior to heat treatment increased the thermal sensitivity of S. agona . This indicated that cold shock has a potential to become a practical method to control pathogens in foods. Knowledge gained from this research project would be valuable in developing new strategies to eliminate foodborne pathogens and ultimately improve the biosafety of these consumable products.
Session 100A, Food Microbiology: General II
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