The many steps and equipment needed to make your own mushroom blocks can be daunting. This method balances time
and cost by eliminating variability with use of fuel pellets and
by-passing sterilization and using pasteurization instead.
Follow the steps below to make your own ready-to-fruit mushroom block:
1. Gather the materials
Multiple blocks can be prepared at one time. Gather all the materials in a clean area, wipe down the counter tops.
2. Prepare the dry materials
Weigh out 2 lbs. of dry hardwood fuel pellets in a plastic container and add a pinch of gypsum to the top. Level out the pellets and make a mark on the container (Figure 1). Later you will add the same volume of boiling water in order to rehydrate the pellets. Add the pellets to a standard 0.2 micron filter patch bag (Figure 2).
Any number of these bags can be prepared ahead of time. You may be limited by the number of blocks that can fit inside the insulated container.
3. Pasteurize the blocks
When you are ready to pasteurize, heat a large pot/barrel of boiling water. When it reaches a rapid boil, use the plastic container with volume mark from Step 2 to add the same volume of water directly to each of the filter patch bags filled with pellets (Figures 3 & 4). Be cautious while working with boiling water. Seal or tightly fold over the bags after adding the water (Figure 5). The pellets will quickly heat and expand. Everything in the bag will pasteurize from the steam. The bags should be packed tightly into storage tubs (or preferably insulated containers that will hold the heat such as a picnic cooler) and allowed to pasteurize for 2 hours (Figure 6).
4. Cool the blocks
After 2 hours, unpack the bags from the insulated container and space them out on wire shelves to cool. This should be done in a clean area if possible, with little traffic and air flow. Be sure the bags are sealed or folded over tightly to reduce the risk of contamination by common molds.
5. Inoculate the blocks
Inoculate the blocks immediately upon cooling. The risk of contamination problems increases over time. Higher inoculation rates tend to reduce contamination problems. We recommend inoculating with grain spawn which may add extra nutrition in the block. Carefully open the fuel pellet bag, pour in approximately 1 lb. grain spawn, fold the top of the bag over, shake to mix, then seal the bag. A rubber band tightly looped works well to seal (Figure 7). Be sure that the filter patch is not blocked so it allows air exchange..
5. Incubate the blocks
Once inoculated, place the blocks in an area where they will not be disturbed for 1-4 weeks. Incubation time varies based on species, temperature and inoculation rate. Blocks should begin to colonize quickly (Figure 8). Store or fruit blocks based on mushroom variety and strain specifics.
Blocks should begin to colonize quickly. These oyster blocks are 8 days old. Overall incubation time varies based on strain.