PURPOSE: To provide an apparatus capable of efficiently sterilizing materials to be treated in a short time for high-pressure treatment by providing a construction for feeding fluid materials to be treated and gaseous carbon dioxide into a treating chamber of a high-pressure treating vessel, pressurizing the aforementioned materials to a high pressure and sterilizing the materials.

CONSTITUTION: A treating chamber 12 for housing fluid materials such as foods to be treated is formed in a cylindrical high-pressure treating vessel 10. The fluid materials to be treated are then fed through a feed passage 30 for the materials to be treated into the treating chamber 12 with a pump 32. Gaseous carbon dioxide from a gaseous carbon dioxide supply source 40 is subsequently fed through a degerming filter 46 and a gaseous carbon dioxide feed passage 38 into the treating chamber 12. A water feed valve 24 of a pressurizing device 14 is then opened to feed high-pressure water formed with a pressurizing pump 22 from a pressurizing passage 20 into bellows 60, which are expanded to pressurize the materials to be treated in the treating chamber 12 and the gaseous carbon dioxide to a high pressure. Thereby, the materials to be treated are sterilized. Germ-free air is subsequently fed from a germ-free air feed passage 58 into the treating chamber 12 to discharge the sterilized materials to be treated from a discharge passage 72. Gaseous carbon dioxide dissolved in the materials to be treated are then removed in a deaerating vessel 74.