Inactivation of Escherihcia coli by high hydrostatic pressure and carbon dioxide

초록

The effect of high hydrostatic pressure treatments combined with carbon dioxide saturation on Escherichia coli (ATCC 11229) in acid pH of citrate buffers (pH 3.5 and 5.5) or apple juice (pH 3.98) were investigated. The CO2 saturation of citrate buffers and apple juice suspensions reduced the pH. The saturation of citrate buffers and apple juice with CO2 prior to HHP treatments more effectively inactivated E. coli than HHP treatments alone. The acid pH of citrate buffer (pH 3.5) combined with HHP treatments effectively inactivated E. coli. Also, apple juice suspensions (pH 3.98) of E. coli were more resistant to HHP treatments than citrate buffer suspensions. A high pressure treatment of 45 Kpsi for 30 sec at 23°C inactivated two logs of E. coli in the apple juice (pH 3.98), three logs of E. coli in the citrate buffer (pH 5.5) or seven logs of E. coli in the citrate buffer (pH 3.5). The recovery of HHP treated E. coli on nonselective tryptic soy agar was greater than on selective violet red bile agar.