Difference between Moist Heat Sterilization & Dry Heat Sterilization
November 19, 2012
There are different processes available through which you can sterilize different materials. To be able to choose the right sterilization process, one must know what method suits the material in question more. You can’t sterilize materials that are heat sensitive with autoclaves. Similarly, you can’t use filter sterilization with chemicals having a greater microbe size when compared with the membrane pores of the filter.
So, to use the dry and the moist heat sterilization in an effective manner, you must understand the difference between both of them.
Moist Heat Sterilization
Water at high pressure level is used in moist heat sterilization. Autoclave is the instrument in which this process is carried out. The temperature of the steam in this method is lower when compared with dry heat sterilization, but the high pressure helps with effective sterilization to take place.
The structural proteins and the organism’s enzymes are destroyed through moist heat. This results in the death of the organisms. Moist heat method is used for heat sensitive materials and materials through which steam is permeable. Culture media is also sterilized through moist heat sterilization.
Through moist heat sterilization, the most resistant of the spores require a temperature of 121°C for around half an hour. It is a more effective method when compared with dry heat sterilization. This can be supported by the fact that through moist heat, sterilization can be achieved at lower temperatures in a shorter duration.
These were the main difference between the dry and the moist heat sterilization methods. If you want to sterilize materials that are more heat sensitive when compared with both these methods, you should go for filter sterilization or chemical decontamination methods.
Dry Heat Sterilization
In dry heat sterilization, dry heat is used for sterilizing different materials. Heated air or fire is used in this process. As compared to the moist heat sterilization, the temperature in this method is higher. The temperature is usually higher than 356° F or 180 °C.
Dry heat helps kill the organisms using the destructive oxidation method. This helps destroy large contaminating bio-molecules such as proteins. The essential cell constituents are destroyed and the organism dies. The temperature is maintained for almost an hour to kill the most difficult of the resistant spores.
Things such as glassware, metal instruments, paper wrapped things and syringes are effectively sterilized through dry heat. The materials used in these things are heat resistant or it can be said that they are heat stable. Powders impermeable to moisture and anhydrous oils and fats can also be sterilized using dry heat sterilization.
Dr. Daniel Prince is president of Gibraltar Laboratories Inc. He has led the Company’s expansion and growth since 1987.
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