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Research
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Virginia Sea Grant funded research The effects of conventional and alternative processing operations on the presence and public health significance of Cryptosporidium parvum in Eastern oysters (Crassostrea virginica) George J. Flick, D. Lindsay, S. Smith, R. Croonenberg, and R. Fayer The overall objective is to determine how contemporary and alternative production and processing procedures reduce or eliminate infectious Cryptosporidium parvum oocysts in oysters. This goal will be achieved through completion of the following; (1) The effects of various customary unit processing operations (i.e., dry storage, shucking, blowing, cold storage) on the parasite in processed product; (2) the effects of depuration and relaying on the parasite in shell oysters; (3) the effects of alternative (i.e., pressure, irradiation, pasteurization) processing operations on the parasite; and (4) the effects of customary preparation methods (thermal and microwave energies) on the parasite. Methods correspond with objectives: (1) Oysters identified as containing C. parvum will be processed according to customary practices and evaluated using a bioassay for infections oocysts with the standard mouse procedure; (2) Oysters containing C. parvum will be placed in a depuration system and others will be relayed to a growing area identified as free from C. parvum. Once the oysters have spent the required number of days in the water and meet the criteria from harvesting, the oysters will be processed under customary conditions and tested for the presence of infectious C. parvum oocysts; (3) Oysters in either the shell or shucked meats (depending upon the study) will be subjected to high hydrostatic pressures, gamma irradiation, and the steam tunnel assisted shucking process. The effects of the various process on the infectivity ability of C. parvum will be determined; and (4) shucked oysters will be subjected to varying thermal and microwave energies to simulate the normal preparation methods in domestic and food service kitchens. The oysters will be evaluated for infectious C. parvum oocysts. Recent scientific literature has reported that oysters harvested in growing waters classified as Approved contain infectious oocysts of the human parasite, C. parvum, and that consumption of the oysters presents a potential human health hazard. This information has the potential of impacting the oyster industry as the recent concern with Vibrio species microorganisms expressed by food regulatory and consumer advocate groups. The research proposed will assist in identifying the actual risk presented by C. parvum through oyster consumption for normal and individuals at risk. |
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Virginia Sea Grant • Virginia Institute of Marine Science |
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