Refining the Post Harvest Processes (PHP) for Raw Oysters in Florida

NON-TECHNICAL SUMMARY: Continuing concerns for food borne illnesses due to consumption of raw oysters have forced federal mandates for implementation of post harvest processing (PHP) techniques that require technical development and verifications. Advance the implementation of post harvest processing (PHP) techiques to improve product safety for raw oyster consumption.
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APPROACH: 1. Improve the freezing methods necessary to significantly reduce natural loads of Vibrio vulnificus without compromising the quality and market acceptance of raw oysters. A. Ultra-freezing techniques (nitrogen immersion) will be refined to account for variable freezing rates and high product yield vs. periodic and seasonal changes in product composition that compromise the influence of this PHP process. B. Blast freezing techniques will be refined relative to modes for product exposure and resulting freezing rates to assure more consistent reductions in Vibrio vulnificus loads. C. Lethality models will be developed for PHP freezing to reduce and eliminate Vibrio vulnificus in raw oysters. 2. All new PHP methods will require formal validations recognized by the respective state and federal regulatory authorities responsible for approving use of product safety declarations that can accompany PHP oysters. The validations will require microbial measures through actual processing. The Aquatic Food Products Lab at the University of Florida will be working with the new industry-based Oyster Lab in Apalachicola to provide the necessary studies. 3. As for PHP validations, the UF and industry-based Oyster Lab will collaborate to develop, install and assist use of new verification procedures to certify the safety of all routine PHP oyster production. A. Verification procedures will require further assessments of the best analytical procedures relative to detection of bacterial culprits, V. vulnificus and convenience in application relative to necessary sampling schemes. B. Resulting verification protocol will be advanced in partnership with the commercial PHP participants and the governing regulatory agency, FL Department of Agriculture and Consumer Services in an effort to establish an acceptable product certification program. 4. The analytical capabilities of the industry-based Oyster Lab will require additional practice, collaborative product assessments and development for new methodology for more efficient product screening. The primary method of choice will be real time PCR methods for total Vibrio vulnificus measures from actual products and harvest waters. The required PCR methodology must be substantiated in actual commercial practice. 5. Formal use of the resulting analytical measures for more efficient monitoring of problematic Vibrios in oysters will require recognition by regulatory authorities, including the Interstate Shellfish Sanitation Conference (ISSC), for inclusion in their established Model Ordinance for Shellfish Commerce. Likewise, support in terms of basic scientific evidence and peer reviews will be required from the research and regulatory expertise about the nation. These issues will be resolved in concurrent phases: A. Preparation and delivery of formal ISSC Issues to establish recognized analytical procedures; B. Collaborative analytical working groups with FDA and neighboring universities.

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PROGRESS: 2006/08 TO 2007/08<BR>
OUTPUTS: Several studies were conducted to resolve quality problems related to oysters processed in nitrogen immersion tunnels as the new PHP option. Trials investigated environmental factors, oyster salt content, harvest water temperatures (seasonality) and geographical location to determine the effect each on the percent defect in the final product. Salt content had the highest impact in preventing freeze fracturing of the oyster meats. In addition, the level of nitrogen in the chamber and the contact time were crucial to prevent meats detaching from the frozen shells. Alternative uses for the defected oyster meats included dried oyster powder, oyster pieces and flavor enhancers for soup stocks. Developments with blast freezing remained the least cost PHP option for reducing the Vibrio vulnificus load especially when the initial numbers are high. Performance of the least cost PHP option was improved when combined with applications of mild heat (heat-shock) followed with the blast freezing. Graduate research projects initiated engineered modeling for predictable pathogen lethality with freezing of oysters. Field research established the Franklin County Oyster Industry Lab (Oyster Lab) in Apalachicola, Florida to assist in the process or equipment validations as well as to evaluate other related parameters in the processing operations such as water quality that could influence the finished product quality and safety. The Oyster lab refined applications of the official and rapid analytical techniques to assure an accurate and quick turn-around on all samples. The Oyster lab and the project personnel have developed a verification protocol that exceeds the federal National Shellfish Sanitation Program's recommendations. The stricter verification protocol was develop in conjunction with the industry members to satisfy not only the regulatory requirements but also the industry buyers that required a guarantee that their products have non-detectable levels of Vibrio at all time. This verification protocol will allow each PHP processor to document, on a weekly basis, that their system is working and will generate a certificate that could be forwarded to any buyer that request documentation. The oyster lab has been equipped with Cephied Real-Time PCR and the lab director has completed the equipment and procedure training. These rapid techniques allow the lab to conduct a larger number of samples in the same amount of time as the official laboratory protocol. Likewise, this research is advancing new methodology for pathogen detection that will be submitted to the ISSC in an effort to make Real-time PCR an official method of analysis for Vibrio bacteria in oysters. <BR> PARTICIPANTS: All project investigators. Two graduate students. Franklin County Seafood Industry Tasl Force. Leavins Seafood. Tommy Wards 13 Mile Brand. Webbs Seafood. ISSC and Florida DACS Bureau of Aquaculture, Shellfish Division. FDA Office of Seafood. <BR> TARGET AUDIENCES: Seafood production (harvester), processors and distributors in Florida and about Gulf of Mexico, plus pertinent regulatory agencies. Including all consumers of oyster products across the nation.
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IMPACT: 2006/08 TO 2007/08<BR>
The new PHP option for reduction of potential pathogens in raw oyster has been significantly improved in terms of efficiency, yields and product quality. New analytical methods (PCR based) and letahlity modelling for detection and prediction of potential pathogens has been advanced with intentions to gain scientific and regulatory approval as official methods. Research efforts have established an oyster industry lab with analytical capabilities linked with validation and verification of PHP operations in support of regulatory approval and buyer acceptance for new PHP products.

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PROGRESS: 2005/08/15 TO 2006/08/15<BR>
A research / service industry laboratory has been established in Franklin County and has been analyzing PHP oyster samples for method validation. The Franklin County Industry lab in coordination with UF-Aquatic Food Products Lab has been running side-by-side sample comparisons between the official FDA / ISSC methodology and quantitative Polymerase Chain Reaction (qPCR) to complete formal application to help secure official recognition of qPCR as an alternative analytical methodology for Vibrio vulnificus. Currently, the developed PHP freezing methods adopted in Florida in conjunction with project assistance have been modified to be more efficient and effective. The project investigators will be submitting formal request to the ISSC to recognize qPCR during the 2007 ISSC Bi-Annual Meeting.
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IMPACT: 2005/08/15 TO 2006/08/15<BR>
Project work has increased the safety and efficiency of PHP oyster processing in the state of Florida. The industry in Florida will be able to reduce the lag time between submitting the PHP samples and the time they obtain results to make the decisions to release product into commerce. This process will help to reduce the cost of operation and limit the cost of the inventory.