Regulatory Control of Histamine Production in North Carolina Harvested Mahi-Mahi (Coryphaena Hippurus) and Yellowfin Tuna (Thunnus Albacares): A HACCP-Based Industry Survey

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Title: Regulatory Control of Histamine Production in North Carolina Harvested Mahi-Mahi (Coryphaena Hippurus) and Yellowfin Tuna (Thunnus Albacares): A HACCP-Based Industry Survey
Author: Allen, Dennis Grey
Advisors: David P. Green, Committee Co-Chair
W. Gregory Cope, Committee Member
Lee-Ann Jaykus, Committee Co-Chair
Abstract: 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&#174; 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%) did not meet the HACCP requirement [uneviscerated tunas exceeding 20 lbs (9.1 Kg) in weight] of achieving an internal temperature of < 50oF (10oC) 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 (<250 ppm in 48 hrs at >15oC). 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.
Date: 2004-07-09
Degree: MS
Discipline: Food Science

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