Freezing as a Post Harvest Process (PHP) for Oysters

1. Freezing as a Post Harvest Process (PHP) for Oysters

2. 2001 ISSC Vv Risk Management Plan • Illness reduction goal based on reported illnesses in California, Florida, Louisiana, and Texas of 40% for years 2005-2006 (average) and 60% for years 2007-2008 (average)

3. April 15, 2003 • California Cracks Down on Hazardous Gulf Coast Oysters • California public health officials today banned the sale of raw oysters harvested in warm months from the Gulf of Mexico because of concerns about bacterial contamination.

4. ISSC Approach • Education to at risk populations and expanded efforts for PHP

5. Consequences for Failure • Raw half shell oysters subjected to an approved PHP to reduce Vv to 30 MPN/g or less during certain months of the year when water temperatures are high • Label “For shucking by a certified dealer” during certain months of the year when water temperatures are high • Close growing water areas for oysters intended for the raw half shell market during certain months of the year when water temperatures are high

6. Freezing as a Post Harvest Process (PHP) for Oysters • The FDA and ISSC have established a formal validation procedure for PHP for oysters

7. PHP Requirements • Process Validation • Equipment Validation • Verification • Revalidation when process fails

8. Processor Requirements • The HACCP plan shall contain process controls to ensure that end point criteria are met for every lot. • Sampling program to periodically verify that the end point criteria are met. • Packing and labeling all shellfish in accordance with all requirements. • Record Keeping

9. Labeling • “Processed for added safety” if all pathogens are reduced to safe levels for the at risk population; • “Processed to reduce (name of target pathogen) to non-detectable levels" if one but not all pathogens are reduced to safe levels for the at risk population and the level is non-detectable; • “Processed to reduce (name of target pathogen) to non-detectable levels for added safety” ”if one but not all pathogens are reduced to safe levels for the at risk population and the level is non-detectable; • A term such as IQF, Pasteurized, Pressure Treated may be substituted for the word “processed.”

10. Validation Protocol • For Validation Testing: • Data on ten processed samples from each of three processing days (total of 30 samples) are required • All oysters on the processing day must come from the same lot • Oysters must contain Vv numbers with an adjusted geometric mean (AGM) MPN of 100,000 per gram as an initial load (now 10,000/g) • A sample will consist of 10-12 oysters

12. IQF Oysters

13. Half Shell Oysters Being Glazed

16. Summary of Results

17. Summary of Results

18. Summary of Results

19. Summary of Results

20. API and PCR Comparisons • Good correlations of MPN numbers for Vv by API and PCR • Vv by API-Total Negative 174 out of 352 samples • Vv by PCR-Total Negative 161 out of 351 samples • (17 positive by PCR, but not by API). Three samples were also negative by PCR, but positive by API. • Total Vp was still present in oysters by PCR when Vv was reduced <30MPN/g as determined by API and PCR

21. Conclusions • Need to refine time/temperature abuse conditions needed to achieve required Vv levels in the test oysters • Protocols should include requirements to continue to analyze oysters at least one additional time for Vv after previous analysis indicated 0, 1 or 2 positive tubes • Initial IQF freezing temperatures and the months when the validation study is conducted may affect the time required in frozen storage needed to reduce Vv numbers to non-detectable levels

22. Acknowledgement • This study was funded by the Virginia Fishery Resource Grants Program (VFRGP) and by the Commercial Fish and Shellfish Technologies Program (CFAST)