Deactivation Analysis of Spores in a High Temperature Gas Using a Coupled Water Diffusion and Heat Transfer Model

Abstract

One of the major mechanisms of deactivating spores is to expose them to elevated temperatures. Experiments carried out in an exposure tube to study the effects on spores in a high temperature gas environment provide evidence of spore deactivation. Microbiological tests show that the more likely reason for spore death is due to either protein damage or some damage to the spore's inner membrane, which are processes that are much slower than heat transfer. 1 In this paper, we employ a coupled water diffusion and heat transfer model to evaluate the associated time constant for the deactivation of spores due to water diffusion. We find that for a standalone spore, the time for diffusion is on the order of 0.1 to several hundred milliseconds and approximately one order of magnitude longer for a spore in an aggregate. This result is in better agreement with the associated time constant of approximately 75ms obtained from the experiment than our previous study that only considered thermal-structural analyses and leads us one step closer to understanding the deactivation mechanism of spores.