Sterilise seed or a wooded substrate

sterilise mushroom substrate

What you will need:sterilise mushroom substrate

  • A stove top
  • A pressure cooker or autoclave
  • Glass containers (Console jars) or breathable filtered bags
  • A suitable wooded substrate (for growing mushrooms) or seed (for producing spawn)
  • Water

The process:

  1. Once your wooded substrate or seed has been hydrated to the required level, fill your glass containers or breathable filtered bags 1/2 to 3/4 full.
  2. Fill your pressure vessel with water to the required level (make sure you have enough water in your pressure cooker to last for 90 minutes.)
  3. Create a platform in the base of the pressure vessel.
  4. Place the glass containers or filtered bags in the pressure vessel on top of the platform you created. Make sure to prop the edges of your plastic bags (polypropylene autoclavable bags) away from the edges of the pressure vessel. You can use tin foil to do this.
  5. Close the lid of the pressure vessel. Leave the pressure valve open for now.
  6. Bring the pressure vessel to boil and allow to steam for 5 – 10 minutes; this allows any air in the vessel to be forced out by the steam.
  7. Close the pressure valve.
  8. Allow the pressure vessel to build up pressure to 15 psi. Make a note of the time and set a timer to 90 minutes.
  9. Adjust the heat on the stove top to keep pressure at 15 psi and pressure sterilize the substrate for 90 minutes.
  10. After 90 minutes turn the heat off and allow the pressure vessel to cool naturally. DO NOT cool down your substrate forcibly by using cold water.
  11. The best place to cool down the vessel would be in a clean room in front of a running flow hood. This is not always possible.
  12. Once cooled, your now sterilized substrate is ready for inoculation.

Only use glass or autoclavable plastic bags in your pressure vessel.

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