36E-92 |
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E. WONG1, T. L. Selby2, Y. Han2, and R. H. Linton2. (1) Escuela de Tecnología de Alimentos, Univ. de Costa Rica, San Pedro de Montes de Oca, San Josè, 4456, Costa Rica, (2) Dept. of Food Science, Purdue Univ., 745 Agriculture Mall Dr., West Lafayette, IN 47907-2009 Orange juice has been associated with several foodborne outbreaks, most of them related to Salmonella spp., known to be transferred from skin to juice during extraction. Therefore, the study of strategies to reduce or eliminate pathogens on orange surfaces is of great importance. Our objectives were to model the reduction of Salmonella spp. on orange surfaces using chlorine dioxide (ClO2) gas treatments and to determine the efficacy of a selected treatment in reducing Escherichia coli O157:H7, Listeria spp., and Shigella spp. Naval organic oranges were spot-inoculated (6.45 cm2) at the calyx, stem and side areas with 7-8 log cfu of a mixed culture of each pathogen, air dried for 1 h at 23o C, and treated with 0.09-0.51 mg/l ClO2 gas for 1-14 min at 23o C and 90% relative humidity. Surviving bacteria on treated areas were recovered and enumerated using a membrane-transfer plating method on tryptic soy agar followed by growing on selective media for each pathogen. A central composite design was used to design experiments and the data was analyzed using a response surface methodology (RSM). Treatments that resulted in a 5-log reduction for Salmonella were chosen from the RSM analysis and then further tested for reduction of E. coli O157:H7, Listeria spp., and Shigella spp. A RSM model was successfully developed and validated, in which ClO2 gas concentration and time are significant factors (P<0.001). Salmonella was significantly reduced (from 2 to >6.0 log) by the ClO2 treatments studied. The treatment at 0.24 mg/l (lowest concentration) for 10 min, having 5-log reduction for Salmonella, also led to 5.4, ≥6.0, and ≥6.7 log reductions for E. coli O157:H7, Listeria, and Shigella, respectively. The recommended ClO2 treatment (0.24 mg/l for 10 min) can be successfully used to reduce pathogens on orange surfaces therefore reducing the risk of derived products.
Session 36E, Fruit & Vegetable Products: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |