15D-10 |
Effect of pH and storage temperature on the destruction of Escherichia coli O157:H7 in apple cider treated with fumaric acid and sodium benzoate |
N. CHIKTHIMMAH, R. B. Beelman, and L. F. LaBorde. Department of Food Science, The Pennsylvania State University, Borland Laboratory, University Park, PA 16802 Unpasteurized apple cider contaminated with E. coli O157:H7 has been implicated in several outbreaks of foodborne illness. In 2001, the FDA issued a final ruling mandating the application of Hazard Analysis and Critical Control Point (HACCP) principles and sanitation standard operating procedures (SSOPs) to processors of fruit and vegetable juices (FDA, 2001). We earlier reported a novel fumaric acid/sodium benzoate preservative treatment that is capable of achieving the FDA-mandated 5-log reduction of E. coli O157:H7 populations in unheated apple cider. Inoculated cider treated with 0.15% fumaric acid and 0.05% sodium benzoate (pH 3.2) required approximately 3 and 6 hr at 25 and 35ºC, respectively to achieve a 5-log reduction in E. coli O157:H7. In this study, destruction of E. coli O157:H7 in apple cider treated with fumaric acid and sodium benzoate was determined under a wide range of pH and storage temperatures to include conditions that may commonly occur in apple cider. Apple cider, inoculated with E. coli O157:H7, was treated with fumaric acid/sodium benzoate (0.15%/0.05%), adjusted to pH 3.2, 3.5, 3.8, and 4.1, and then stored at 5, 15, 25, or 35°C. E. coli O157:H7 destruction was significantly greater at higher storage temperatures and lower pH values (p < 0.001). At 5ºC, cider containing fumaric acid/sodium benzoate (0.15% /0.05%) and adjusted to pH 3.2 required 92 hrs to achieve a 5-log reduction. An increase in pH to 3.8 increased the required time to 342 hrs. A significant interaction existed between pH and storage temperature on the destruction of E. coli O157:H7 in apple cider. The results from this study demonstrate a practical method for producing safe apple cider that is an alternative to costly thermal pasteurization. The data can be used by cider makers to establish critical control points for pH, storage time and storage temperature.
Session 15D, Food Microbiology: Fruits and vegetables
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