Mode of Action/Principle of Moist Heat sterilization
Moist heat destroys microorganisms by the irreversible denaturation of enzymes and structural proteins.
The temperature at which denaturation occurs varies inversely with the amount of water present. Sterilization in saturated steam thus requires precise control of time, temperature, and pressure.
Pressure serves as a means to obtain the high temperatures necessary to quickly kill microorganisms. Specific temperatures must be obtained to ensure the microbicidal activity. Minimum sterilization time should be measured from the moment when all the materials to be sterilized have reached the required temperature throughout.
The recommendations for sterilization in an autoclave are 15 minutes at 121-124 °C (200 kPa). The temperature should be used to control and monitor the process; the pressure is mainly used to obtain the required steam temperature. Alternative conditions, with different combinations of time and temperature, are given below.