James M. Hungerford

Scombroid poisoning: A review

Scombroid poisoning, also called histamine fish poisoning, is an allergy-like form of food poisoning that continues to be a major problem in seafood safety. The exact role of histamine in scombroid poisoning is not straightforward. Deviations from the expected dose-response have led to the advancement of various possible mechanisms of toxicity, none of them proven. Histamine action levels are used in regulation until more is known about the mechanism of scombroid poisoning. Scombroid poisoning and histamine are correlated but complicated. Victims of scombroid poisoning respond well to antihistamines, and chemical analyses of fish implicated in scombroid poisoning generally reveal elevated levels of histamine. Scombroid poisoning is unique among the seafood toxins since it results from product mishandling rather than contamination from other trophic levels. Inadequate cooling following harvest promotes bacterial histamine production, and can result in outbreaks of scombroid poisoning. Fish with high levels of free histidine, the enzyme substrate converted to histamine by bacterial histidine decarboxylase, are those most often implicated in scombroid poisoning. Laboratory methods and screening methods for detecting histamine are available in abundance, but need to be compared and validated to harmonize testing. Successful field testing, including dockside or on-board testing needed to augment HACCP efforts will have to integrate rapid and simplified detection methods with simplified and rapid sampling and extraction. Otherwise, time-consuming sample preparation reduces the impact of gains in detection speed on the overall analysis time.

Flow-injection assay of enzyme inhibition in fish using immobilized diamine oxidase

Abstract A flow-injection assay for inhibition of diamine oxidase (DAO) is described. Histamine is decomposed fish is detected and used as the enzyme substrate. Sample extracts are doubly injected; one of the two resulting sample zones is passed through a reactor containing DAO immobilized to Sepharose. Histamine is detected sequentially in both the pristine and enzymatically treated zones. The detection chemistry (kinetics-optimized condensation with phthalic dicarboxaldehyde) allows the selective detection of histamine. Subsequent calibration with histamine standard and comparison of the two peak heights allows generic detection of compounds inhibiting the DAO-mediated conversion of histamine. Preliminary data show that the system can detect inhibitors in extracts of decomposed Mahi-Mahi (associated with a Scombroid poisoning outbreak) and that far lower levels of inhibition are observed in fresh fish. Several known inhibitors and competitive substrates of DAO are also tested.

Determination of tri-n-butyltin in oysters by reaction—gas chromatography of hydride derivatives

A reaction-gas chromatography method for determining tri-n-butyltin (TBT) as the hydride derivative has been adapted to allow determination of TBT in oysters. The extraction method has been modified to prevent fouling of the hydride formation reactor and the gas chromatography has been made faster by employing a different column and temperature program. The detection limit is 3-6 ng/g in oyster tissue. Apparent recoveries of TBT from oyster tissue at 25 and 125 ng/g levels are 107 and 97%, respectively.

Total volatile acids : temperature dependent decomposition indicator in halibut determined by flow injection analysis

Total volatile acids (TVA) is a well known indicator for the decomposition of seafood products. A flow injection analysis (FIA) method, using a gas diffusion cell at elevated temperature, was developed for the determination of TVA in fish and applied to halibut. The FIA method is simple and rapid. The results of this study indicate that the correlation between levels of TVA and degree of decomposition is temperature dependent.

Validation of the Biofish-300 HIS Enzymatic Biosensor for the Detection of Histamine in Fishery Products

The Biofish-300 HIS method is a simple, reliable, and specific enzymatic biosensor for the detection of histamine. This technology is highly specific and selective and allows quantification of histamine in fishery products (fresh/frozen and processed) in a short time frame (2-3 min). Histamine in raw tuna, raw mackerel, raw sardine, raw anchovy, boiled tuna, canned tuna in water, canned tuna in oil, canned mackerel in tomato sauce, canned pickled sardine, and canned salted anchovy was analyzed using a water-based extract. Matrix-specific assay procedures and calibration curves were used to enable analyses to be carried out across multiple sample types. The performance of this assay was examined using samples that were naturally contaminated (reference materials and interlaboratory studies) and spiked with histamine. All data were judged against previously established acceptance criteria. Performance measures were evaluated for linearity, selectivity, matrix, lot consistency, and robustness. Results produced in all performance measures, except robustness, were within acceptable ranges. Out-of-range robustness results reflected deviation in sample volume compared to the standard assay procedures. Positive interferences from the presence of agmatine were shown.