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Normal pressure sterilization and high pressure sterilization

1. Sterilization principle

Whether it is normal pressure or high pressure, or vacuum autoclave, steam sterilization is used, 

the only difference is the pressure. The principle is: saturated steam has strong penetrability. When

 steam contacts the sterilized items, it will release a lot of latent heat. Under the action of steam heat,

 the hydrogen bonds in the molecules of the bacterial proteins in the culture medium are broken, 

resulting in bacterial death.

2. The development and evolution of normal pressure and high pressure autoclaves

Chinese edible fungi have developed from simple earth stove normal pressure sterilization to

 steam-supplied Mongolian yurt autoclaves, round single-door straight-cylinder autoclaves,

 and then horizontal single-door autoclaves.

3. Normal pressure autoclaves

Enterprises that continuously produce cultivation bags mostly use high pressure sterilization. 

Seasonal Ganoderma lucidum cultivation professionals only use the sterilization process for 3 

months a year, so they do not purchase autoclaves. Instead, they use manual forklifts to push 

the sterilization cart loaded with Ganoderma lucidum short-section wood cultivation bags into

 a simple normal pressure sterilization room built with canvas. Two small boilers supply steam 

at normal pressure (steam volume 0.5 tons/hour). It only takes 3 to 4 hours to quickly rise to 

102°C and maintain it for more than 14 hours. It must be kept warm for another 12 hours without

 dropping the temperature to sterilize thoroughly.

4. Single-door autoclave

Single-door autoclaves are extended from the food canning industry. Food cans are sterilized in 

closed containers, while edible fungus cultivation bags are sterilized in semi-closed containers.

There is an essential difference between the two. Therefore, when the edible and medicinal fungus

cultivation bags are removed from the autoclave after sterilization, "backsucking" will occur due 

to the pressure difference between the inside and outside of the cultivation bags, resulting in

contamination. Therefore, more than a decade ago, the production requirements for cotton filter 

plugs used on cultivation bags were quite high.