Abstract
A simplified method for measuring histamine formation in bacterial cultures is described. Histamine production by Proteus morganil, Proteus vulgaris and Hafnia alvei cultures isolated from spoiled skipjack tuna was measured under twelve environmental conditions. The highest histamine concentrations were found at 19°C and 30°C depending on the bacterial species and the environmental parameter. No histamine was formed at 1°C, indicating that the rapid cooling of tuna flesh to freezing temperatures may adequately suppress histamine formation. At 19°C and 30°C, the Proteus organisms at first formed high levels of histamine, much of which was subsequently destroyed; histamine concentrations in these cultures eventually stabilized at 150 to 200mg/100ml. These observations indicate that the concentration of histamine in tuna products may depend on an equilibrium between histamine production and destruction.
