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Development of Model Scombrotoxin Control Procedures for Commercial Atlantic Fish Species


The goal of the project is to provide information to the U.S. Environmental Protection (EPA) agency and aquaculture producers on the human pathogens present in recirculating and flow-through aquaculture systems and may be introduced into receiving waters. Specifically, <ol> <li>Identify and quantify histamine-forming bacteria found on selected fish species and fish contact surfaces on cooperating fishing vessels and processing plants (first receivers);
<li>Determine levels of histamine in potentially scombrotoxic species (yellowfin tuna, mahi-mahi, Atlantic mackerel, bluefish, Spanish mackerel) and, when present at concentrations above 50 ppm, determine levels of cadaverine and putrescine;
<li>Monitor the internal temperature of selected fish species from time of harvest (inshore and offshore boats) to point of processing or shipping;
<li>Determine the variable(s) that best predict the development of a histamine hazard;
<li>Develop one or more HACCP models that adequately control histamine;
<li>Repeat steps 1-6 after implementation of the selected HACCP models; and
<li>Prepare written educational materials and conduct programs for industry, advisory, and regulatory audiences.</ol>

More information

The mandatory FDA HACCP regulation requires seafood dealers to ensure that products are safe from chemical, biological, and physical hazards. However, histamine poisoning continues as a seafood hazard. This project will reduce histamine poisoning caused through fish consumption and increase firm profitability by minimizing unnecessary product loss.
Information from the research will determine whether and what treatment, if any, may be required by aquaculture producers to comply with anticipated EPA discharge standards. The research will also provide information to recirculating aquaculture firms on the potential health risks their employees may experience. The research will include marine and fresh water species as well as cold and warm water fish. A survey will be performed on aquaculture systems to determine the presence and concentrations of human pathogens in biofilms on equipment and structures. Pathogens in growing waters, discharges and receiving waters will also be determined and their relative concentrations determined where possible. The relationship between production parameters, such as, loading capacity and feeding, will be determined by measuring chemical and physical water quality parameters such as total organic carbon, total soluble solids, setteable solids, TKN, NH3, ortho-phosphate, flow rate, temperature, and turbidity. The possible relationship between pathogen presence in receiving waters and type of production system will be determined by evaluating receiving water quality at, above, and several distances below effluent discharges. Project goals will be accomplished by visiting production facilities varying in production volumes two times during the year. Aquaculture facilities will be sampled from New Hampshire to Louisiana in attempt to normalize the research results. All of the biological, chemical, and physical analyses will be determined according to established procedures. The sampling protocol will be finalized once the variation in system sampling is established. Research results will be statistically analyzed and submitted to scientific and trade publications for dissemination.
Histamine poisoning is one of the most common chemically induced seafood borne illnesses reported in the United States today. Generally it is believed that the causative agents are biogenic amines (histamine, putrescine and cadaverine) produced by Gram negative bacteria. Under the U.S. Food and Drug Administration's HACCP program, growth of histamine producing bacteria in potentially hazardous fish is controlled primarily by limiting time and temperature conditions. The purpose of this study was to determine if current regulatory guidelines are being meet for the control of histamine production in North Carolina harvested mahi mahi and yellowfin tuna, and if not, what potential food safety risks may likely occur. Twenty nine composite fish muscle samples were obtained from 18 mahi mahi and 11 yellowfin tuna troll caught and analyzed for their histamine content. No sample analyzed exceeded 2 ppm histamine, the detection threshold for Neogen's ELISA based Veratox rapid test. Fish internal temperatures were continuously monitored from point of harvest through primary processing to determine individual fish cooling rates. Mahi-mahi were chilled on ice within 12 hrs of harvest as required under the federal HACCP guidelines. Generally, yellowfin tuna (60 percent) did not meet the HACCP requirement [uneviscerated tunas exceeding 20 lbs (9.1 Kg) in weight] of achieving an internal temperature of less than 50 degrees F (10 degrees C) in 6 hrs. Three hundred and eighty six composite fish muscle and environmental samples were screened for the presence of histamine producing bacteria. Twenty six percent of 549 isolates selected based on their morphological characteristics tested positive on Niven's media. Sixty three Niven's positive isolates were Gram negative rods and 58 were Gram positive. The Beckon Dickinson BBL Crystal method was used primarily for identification of Gram positive isolates since the API 20E Enterobacteriaceae identification test is specific for the identification of Gram negative bacteria. Neither API 20E test nor BBL Crystal method was able to identify every Niven's positive isolate. Only five of forty three isolates tested were confirmed and classified as low histamine producers (less than 250 ppm in 48 hrs at more than 15 degrees C). Three Gram negative isolates were identified as Enterobacter cloacae. Two Gram positive isolates were identified as Staphylococcus kloosii. This study contradicts the general belief that Gram negative bacteria are solely responsible for histamine production in potentially hazardous fish. The confirmation of histamine producing bacteria found in this study demonstrates the potential risk for histamine production. However, no detectable levels were found in the fish muscle samples analyzed, even though yellowfin tuna did not meet the regulatory HACCP guidelines. Therefore no food safety risks were found under commercial conditions studied.
The ability to include both commercial fish processors and charter boats in the study provides a comprehensive approach to idetifying the scombrotoxin probelm. Once the impact of each fishery is identified, specific activities will be developed to address the problem. This project should result in the marketing of high quality, safe fish.

Flick Jr, George
Virginia Polytechnic Institute and State University
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