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Effects of high pressure process on Vibrio parahaemolyticus in pure culture and in Pacific oysters |
H. CALIK1, M. T. Morrissey1, P. W. Reno2, and H. An3. (1) Food Science and Technology Department, Oregon State University, OSU Seafood Laboratory, Marine Drive Rm 253, Astoria, OR 97103, (2) Department of Microbiology, Oregon State University, Hatfield Marine Science Center, 2030 Marine Science Drive, Newport, OR 97365, (3) Department of Nutrition and Food Science, Auburn University, 362 Spidle Hall, AL 36849-5605
Several cases of Vibrio parahaemolyticus (Vp)-induced gastroenteritis occurred in the Pacific Northwest due to consumption of raw oysters. High Pressure Process (HPP) Technology has shown good potential in reducing pathogens. Objectives of this study were to determine the effect of HPP treatment on pure clinical and environmental Vp cultures and on Vp strains inoculated in Pacific shell-oysters and to establish optimum HPP conditions (time/pressure) for inactivation of Vp. Effect of HPP treatment on pure Vp culture was tested using clinical and environmental strains that were acquired from American Type Culture Collection (Manassas, VA) and from FDA (Seattle, WA), respectively. Both clinical and environmental Vp strains were treated with HPP at different settings (1-10 min at 241 MPa; 1-5 min at 276 MPa; 30-120 s at 310 MPa; 10-90 s at 345 MPa). Shell-oysters were inoculated with clinical and environmental Vp strains and tests were performed to determine if Vp in shell-oysters respond to HPP treatment differently than Vp in pure culture. Oysters were treated at the same time and pressure settings. Total Vp was enumerated before and after treatment to determine Vp survival. Results showed that Vp is susceptible to HPP both in pure culture and in shell-oyster treatments. Optimum conditions for reducing Vp counts in pure culture and in shell-oysters from 109 cfu/ml to 101 cfu/ml were achieved at 345 MPa in 30 s and at 345 MPa in 90 s, respectively. At 241 MPa, more than 10 min were required to reduce the count to 101 cfu/ml Vp survival in both conditions. Slight resistance variations to HPP were detected between clinical and environmental Vp strains in pure culture and in shell-oysters. HPP is a viable means to reduce the Vp counts in oysters. Outbreaks due to ingesting Vp infected raw oysters could be prevented using HPP technology.
Session 42, Seafood Technology: Safety, Processing
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