Inactivation of Salmonella typhimurium by high pressure carbon dioxide

Thermal inactivation of Salmonella typhimurium was studied under CO2 pressures of 15, 30 and 60 atm at 25 35 and 45 degrees C Two phases were observed in the destruction curves The earlier stage was characterized by a slow rate of inactivation in the number of S. typhimurium, which increased sharply at the later stage. it was suggested that the cell death resulted from the lowered pH due to solubilization of CO2. An increase of pressure and/or temperature enhanced the antimicrobial effects of CO2. Salmonella typhimurium suspended in physiological saline (PS) was completely inactivated under 60 atm CO2 treatment in 35 and 15 min at 25 and 35 degrees C, respectively On the other hand, it was completely inactivated when suspended in PS containing brain-heart infusion broth for 140 and 100 min. A minimum D-value was obtained cinder 60 atm CO2 pressure at 45 degrees C. Inactivation rates of S. typhimurium were sensitive to pressure, temperature, exposure time, initial number of cells, and the suspending medium. (C) 2000 Academic Press.