a b s t r a c t
The present work describes a novel multiple sensor-type system for the real-time analysis of aseptic
sterilisation processes employing gaseous hydrogen peroxide (H2O2) as a sterilant. The inactivation kinetics
of Bacillus atrophaeus by gaseous H2O2 have been investigated by means of a methodical calibration
experiment, taking into account the process variables H2O2 concentration, humidity and gas
temperature. It has been found that the microbicidal effectiveness at H2O2 concentrations above 2% v/v is
largely determined by the concentration itself, while at lower H2O2 concentrations, the gas temperature
and humidity play a leading role. Furthermore, the responses of different types of gas sensors towards
the influencing factors of the sterilisation process have been analysed within the same experiment. Based
on a correlation established between the inactivation kinetics and the sensor responses, a calorimetric
H2O2 sensor and a metal-oxide semiconductor (MOX) sensor have been identified as possible candidates
for monitoring the microbicidal effectiveness of aseptic sterilisation processes employing gaseous H2O2.
Therefore, two linear models that describe the relationship between sensor response and microbicidal
effectiveness have been proposed.