Effects of on-board and dockside handling on the formation of biogenic amines in mahimahi (Coryphaena hippurus), skipjack tuna (Katsuwonus pelamis), and yellowfin tuna (Thunnus albacares).

Consumer illnesses by scombroid poisonings have been a continuing problem for many years. The intoxications follow the ingestion of fish such as tuna and mahimahi that have undergone bacterial decomposition, leading to the formation of biogenic amines. Research studies have concluded that histamine is one of the indicators of scombrotoxic fish and that other amines, such as cadaverine, could be involved in the illnesses. Guidance for the handling of fish on board fishing vessels to prevent the production of scombrotoxic fish has been limited by a lack of data addressing changes that occur in fish from the water to delivery at dockside. In this study, the changes in selected biogenic amines were determined in mahimahi and tuna, which were captured and held in seawater at 25 to 35 degrees C for incubation times up to 18 h. The fillets from the treated fish were sectioned by transverse cuts and analyzed for histamine, cadaverine, and putrescine. Results showed that at 26 degrees C, more than 12 h of incubation were required before a histamine concentration of 50 ppm was reached in mahimahi. At 35 degrees C, 50 ppm histamine formed within 9 h. Similar results were found for skipjack and yellowfin tuna. Histamine concentrations exceeded 500 ppm within an additional 3 h of incubation in mahimahi. At both temperatures, an increase in the concentration of cadaverine preceded an increase in histamine levels. Changes in putrescine concentrations in the fish were less pronounced. The study also demonstrated that histidine decarboxylase activity was retained in some frozen samples of fish and could result in further increases in histamine on thawing.

Gas chromatographic method for putrescine and cadaverine in shrimp.

A gas-liquid chromatographic method developed for the determination of putrescine and cadaverine in fishery products was modified for application to the determination of diamines in shrimp. Addition of potassium chloride and hydrochloric acid to the methanol-water extraction solvent resulted in increased recovery of the diamines and minimized gel formation. The recovery of putrescine increased on average from 64 to 98%, and the recovery of cadaverine increased from 85 to 93%. The chromatographic separation of the derivatized diamines was significantly improved with a change from an OV-225 column (cyanopropyl methyl phenyl methyl silicone) to a more polar HP-Innowax column (crosslinked polyethylene glycol). Background levels of putrescine and cadaverine in known high-quality shrimp ranged from 0 to 0.7 ppm. Shrimp that failed sensory examination generally contained putrescine at levels >4.8 ppm and cadaverine at levels >1.3 ppm.

Fresh and Frozen Shrimp: A Profile of Filth, Microbiologica! Contamination, and Decomposition.

A 2-year nationwide survey was conducted by the Food and Drug Administration to provide current information about filth, decomposition, and microbiological contamination of domestic and imported fresh and frozen shrimp. Whole or equivalent filth insects, mostly ants, were found in 14.4% of the samples. Of countries contributing at least 10 samples for filth analysis, India had the highest percentage positive for filth insects (45.5%); the United States had the lowest (6.3%). Filth insect fragments were present in 5.4% of the samples. Incidental insects were present in 6.3% of the samples, with flies the most commonly found. Of countries contributing at least 10 samples for filth analysis, India had the highest percentage positive for incidental insects (27.3%); Ecuador had the lowest (2.3%). Unidentified insect fragments were found in 33.3% of the samples; cockroach excreta pellets were present in 2.1%, rat or mouse hairs in 5.7%, and other striated animal hairs in 15.3%. Of countries contributing at least 10 samples for filth analysis, the Philippines had the highest percentages positive (30.0 and 50.0%) for rat or mouse hairs and other striated hairs, respectively; Malaysia was close behind with 23.1 and 46.2%. Samples from the United States had the lowest percentage positive for rat or mouse hairs (0.9%) and other striated hairs (7.2%). Listeria spp. were found in 6.8% of the samples; Salmonella spp. were found in 8.1%. Some level of decomposition was observed in 15.4% of the samples tested organoleptically.