What Is Moist Heat Sterilization?

Moist heat sterilization is a technique that uses heated water and superheated steam to disinfect contaminated materials, such as culture media, surgical instruments, glassware and other non-thermally sensitive items. One form of moist heat sterilization is known as autoclaving, where the most effective standard conditions include a 15-minute exposure inside a vessel that is subjected to a pressure level of 15 pounds per square inch and a temperature of 250 degrees Fahrenheit.

Sterilization is the process of thoroughly destroying microbial growth that may potentially become a health hazard. There are various sterilization methods or anti-microbial treatments. The efficacy of these procedures depend on several factors, including the properties and quantity of microbes present, environmental impacts and the length of exposure to contaminants.

Heat is one of the most effective physical agents used in sterilization, where the structural proteins and enzymes of microbes are completely denatured. Aside from moist heat sterilization, common heat treatments also include direct flame, dry heat, tyndallization and pasteurization.

The two forms of moist heat sterilization include boiling and autoclaving. Boiling is less effective compared to autoclaving since some microbes, such as endospore-forming bacteria and protozoan cysts are resistant to boiling. Autoclaving offers a better alternative to boiling, which delivers double the amount of heat energy compared to steaming alone. At standard operating conditions, autoclaving is known to destroy all vegetative cells, endospores, viruses and cysts of protists.