Thermal death times of Hafnia alvei cells in a model suspension and in artificially contaminated hot-smoked kahawai (Arripis trutta).

In New Zealand the product most frequently implicated in cases of scombroid poisoning is hot-smoked kahawai (Arripis trutta). Using a Hafnia alvei strain, previously isolated from a portion of hot-smoked kahawai with a histamine level of 1,659.4 mg/kg, thermal death trials were carried out in a model suspension (0.1% peptone) at 54, 55, 56, 57, and 58 degrees C. From the linear regression line (R2 = 0.98) fitted to observed D values plotted against temperature, calculated D values for 54, 55, 56, 57, and 58 degrees C were estimated to be 0.63, 0.36, 0.20, 0.11, and 0.06 min, respectively, giving a z value of 4.14 degrees C. Thermal death trials were also carried out for H. alvei associated with hot-smoked kahawai at 54, 55, 55.5, 56, and 57 degrees C. From the linear regression line (R2 = 0.93) fitted to the data, calculated D values for 54, 55, 56, and 57 degrees C were estimated to be 1.42, 0.74, 0.38, and 0.20 min, respectively, giving a z value of 3.57 degrees C. Results indicate that hot smoking has the potential to eliminate H. alvei from seafood products.