Changes in Histamine Content in Fish Products for Animal Feeds and in Aqueous Solution by Gamma-Irradiation

The irradiation effects on histamine in fish meals and fish solubles for animal feeds and in aqueous solution were investigated. The amount of histamine in fish meal (0.4mg/100g) was not changed by up to 5.0 Mrad (50kGy), while the histamine content in fish soluble (45.7 mg/100 g) decreased ca. 16% at 5.0 Mrad. There occurred no accumulation of histamine by irradiation or during storage.

The G values of histamine formation from histidine solution and histamine decomposition by irradiation in deoxygenated neutral solutions were 0.077 and 1.90, respectively. Oxygen inhibited the formation of histamine from histidine but it had little effect on histamine decomposition. Nitrous oxide accelerated the decomposition of histamine and inhibited the accumulation of histamine in histidine solution by irradiation. These results show that there is no problem of histamine accumulation in feedstuffs caused by irradiation since the decomposition of histamine is preferred to its formation.