Hot wet method and dry method were all physical disinfection sterilization method of thermodynamic factor to kill microorganisms, but their sterilization mechanism is different, the hot and humid method mainly through microbial protein killed, solidification by dehydration dry law of protein oxidation, degeneration, carbonization and electrolyte concentration poisoning death to kill microorganisms.Their operation characteristics are also different, and the fundamental difference lies in the difference between the heating environment and the humidity level of the microbial cells during the disinfection and sterilization treatment:”Damp-heat” heating refers to the heating in which both the internal and the heating environment of microorganisms are in a state of humidity saturation. At this point, the microorganisms are in a state of equilibrium with pure water or saturated steam.”Dry heat” heating, on the other hand, refers to heating in a heated environment without water or without sufficient humidity saturation, which can be zero or just below saturation.
In general, microorganisms have a stronger resistance to heat than those with hot and humid conditions, that is, the temperature required for wet and hot coagulation of proteins is much lower than that required for dry and hot oxidation of proteins to kill microorganisms. Moreover, the presence of water is conducive to protein coagulation. In the local environment under thermal action, the more water or the higher the humidity is, the lower the temperature required for protein coagulation, the faster the coagulation speed is, and the better the killing effect of the external device is.In addition, humid heat is more penetrating than dry heat because steam and water conduct heat more efficiently than air. Secondly, a large amount of latent heat is released during the condensation of steam, which can make the object heated rapidly. It is precisely because of the difference in the sterilization mechanism and heating characteristics of the two, the hot and humid sterilization is not only reliable, but also can reduce the sterilization temperature and reduce the action time.