Impact of dissociation equilibrium shift on bacterial spore inactivation by heat and pressure

The shift of the dissociation equilibrium tinder pressure and temperature plays a decisive role in the inactivation of bacterial spores. To obtain the dissociation equilibrium shift in water and buffer systems, the thermodynamic dissociation constants in a wide range of pressure and temperature were modelled. Heat and pressure inactivation of Geobacillus stearothermophilus spores at diflerent initial pH-values in ACES and phosphate buffer confirmed the modelled data. Thermal inactivation in both buffers at 114, 122 and 127 degrees C resulted in higher logarithmic reductions with ACES. Contrary, after pressure treatment at 500, 600 and 900 MPa with 80 degrees C phosphate buffer showed higher inactivation. These results indicated the different dissociation equilibrium shifts in buffer systems by heat and pressure. (C) 2008 Elsevier Ltd. All rights reserved.