A sterilizing apparatus (10, 80) includes an enclosure (18, 84) defining an interior chamber (20, 86) and a door (22) for accessing the interior chamber (20, 86). A fluid source (42, 88) communicates with the chamber (20, 86) to supply a working fluid thereto. A heater (64, 102) heats the fluid in the chamber (20, 86) and a pump (62, 82) moves the fluid in the chamber (20, 86) by the heater (64, 102). A valve (50, 150) communicates with the chamber (20, 86) and with the exterior of the chamber (20, 86) and is configured to vent the fluid in the chamber (20, 86) to the exterior at a pressure of approximately one atmosphere. Such provides superheating and concentrating of the working fluid in the chamber (20, 86). A method of sterilization includes introducing a working fluid into an interior chamber (20, 86) and circulating the fluid through at least one recirculation loop (54, 96) having a heater (64, 102) for heating the fluid to an operational temperature suitable for killing microorganisms. The method further provides venting of the fluid from the chamber (20, 86) so as to maintain the pressure at approximately one atmosphere. The method further provides for killing of very high temperature resistant microorganisms.
