4 °C - the National Sea Grant Library

Temperature is an important factor to be considered in relationship to the food
product of concern. In preparing, packaging and shipping food products,
temperatures may fluctuate during handling. In this discussion, a single temperature
of irradiation (20°C) will be considered.
The use of 20°C, as an irradiation processing temperature, is commercially
applicable to dry spices, fruits and vegetables. The generation time for L.
monocytogenes in TSB at 20°C was approximately 1.39 h (Andrews, 1994).
Generation time is an important factor to consider in determining the ability of
L.monocytogenes to recover from sublethal irradiation. This was especially a concern
during these experiments since the available irradiation source was low with an
emission rate of 18 Gy/min, compared with commercial irradiation facilities emitting
100’s Gy/min.
Results of split dose irradiation of L.monocytogenes at 20°C with an initial
cell concentration 10 9 CFU/ml TSB are presented in Figure la. When comparing the
control versus the composite of split dose, the survival curves appear to be quite
similar. However, in calculating the D-Values using linear regression analysis, there
were statistical differences (p