Freezing as a Post Harvest Process PHP for Oysters

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

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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.

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ISSC Approach

• Education to at risk populations and expanded
  efforts for PHP

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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

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Freezing as a Post Harvest Process (PHP) for
Oysters

• The FDA and ISSC have established a formal
  validation procedure for PHP for oysters

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PHP Requirements

• Process Validation
• Equipment Validation
• Verification
• Revalidation when process fails

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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

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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.

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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

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IQF Oysters
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Half Shell Oysters Being Glazed
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Summary of Results
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Summary of Results
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Summary of Results
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Summary of Results
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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 lt30MPN/g as determined by API and
  PCR

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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

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Acknowledgement

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