Effectiveness of gamma irradiation in the inactivation of histamine-producing bacteria

Exposure assessment and semi-quantitative risk analysis of histamine in tuna and tuna-like fish from Indonesia

This study aimed to investigate histamine exposure associated with consumption of fresh tuna and tuna-like species in West Java, and to estimate risk of Scombroid Fish Poisoning (SFP) in Indonesia. A range of species, including tuna (Thunnus spp.), bullet tuna (Auxis sp.), and skipjack (Katsuwonus pelamis) were collected from local markets and fish landing sites. Subsequently, histamine concentrations were determined using NMR analysis and exposure was calculated in mg/day for toddlers, children, and adults. The results showed that skipjack had the highest histamine exposure for all age groups, followed by bullet and regular tuna. The highest EDI for histamine was from skipjack consumption, accounting for 38.67; 37.77 and 20.74 percentage of exposure for toddlers, children and adults, respectively. These values are below the defined thresholds levels (ARfD), indicating no potential risk of acute health effect. Cooked bullet tuna and skipjack were estimated to cause similar illnesses, accounting for 6-7 cases per 100,000 individuals, which was higher than cooked tuna at 1-2 cases per 100,000 individuals. Considering the preparation of raw tuna in restaurants following Good Hygienic Practices (GHP), the predicted annual cases decreased significantly to 4-5 cases per million individuals. This risk estimation only considered histamine levels in fresh fish, without including data from fish preparation. Therefore, further studies were recommended to estimate the risk level in raw/fresh tuna and similar species before consumption.

Survival and Histamine Production by Histamine-Forming Bacteria Exposed to Low Doses of Gamma Irradiation

ABSTRACT

Histamine poisoning occurs when fish containing high amount of histamine are consumed. Because histamine is thermally stable, control of histamine-forming bacteria in seafood is an appropriate strategy for preventing the formation of histamine. One prevention method is the use of gamma irradiation on the histamine formers. To understand the effect of gamma irradiation on the histamine-forming bacteria, laboratory isolates of the prolific histamine formers Morganella morganii, Klebsiella variicola, and Proteus vulgaris were exposed to various doses of gamma radiation in nutrient broth and tuna muscle spiked with histamine formers. None of the test bacteria survived in tuna muscle irradiated at 2.0 kGy. K. variicola was highly sensitive to gamma irradiation and was eliminated at a dose of 1.5 kGy. Histamine production also was reduced significantly as the radiation dose increased. These results suggest that gamma irradiation can effectively eliminate histamine-forming bacteria and reduce the threat of histamine poisoning from seafood.

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