By: FloCube // https://flocube.com/2022/03/03/4-steps-to-making-grain-spawn/
- Step 1: Rinse and clean the grains, then soak in water for 12–24 hours.
- Step 2: Cook the grains, bring to a boil, then simmer for 15–20 minutes to absorb water.
- Step 3: Drain and dry excess moisture from the outside of the grains.
- Step 4: Load grain into mason jars/bags and sterilize for 120–180 minutes at 15 PSI
You can apply this method to all types of grains. Sterilization time depends on the size of the pressure cooker or autoclave you are using, as well as putting spacers between your bags to ensure each jar/bag will reach proper internal temperature to sterilize. Better to over cook than under cook.
Before loading your grain jars or bags, make sure the grains are dry enough. An easy test is to grab a paper towel and lay a few grains from the middle of your batch. Leave for 15 seconds. Then remove the grains and look for wet spots on the paper towel. If there’s a damp spot, your grains are still too wet. The paper towel should be dry. Once you can complete this test, it’s safe to load them in jars or bags for sterilization.
For grain spawn jars or bags, for a bit of insurance, add a small layer of vermiculite at the bottom of your grain jars, then fill them with grains on top. If your grains are overhydrated, the vermiculite will assist by soaking up excess moisture instead of pooling at the bottom of the jar smothering the grain.
Excess water pooling at the bottom of the jar or bag is a breeding ground for bacterial endospores. So it’s best to dump jars like this out and start over.
When dealing with substrate, you must test moisture content before pasteurization or mixed with spawn. Whichever comes first for the method you are using.
Do a field capacity test by grabbing a handful of your hydrated substrate and squeezing it hard. If you see more than a few drops of water drip from your hand, it’s overhydrated. Depending on how overhydrated, you might be able to get away with just adding some vermiculite. However, it may be best to start over and add some more dry substrate to your mixture to get it to field capacity.
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