Monday, 9 November 2015

Making mushroom spawn

Once our LC is ready (you'll probably need several attempts), it's time to use it. However, it isn't a good idea to inject it directly on the final substrate (straw, sawdust, wood logs etc.). This is because growth would be too slow, exposing all at risk of contamination, or it may not even start. You will then need an intermediate step, in order to give our mycelium some extra advantage, allowing it to grow quickly and aggressively. This intermediate step is, in fact, the preparation of the "spawn". Mushroom spawn is a way to multiply mycelium, obtaining enough of it to be able to inoculate the final substrate. The most widely used method is to use seeds of cereals, hydrated and sterilized: their high protein and carbohydrates content will allow the mycelium to grow vigorously and rapidly.
However, seeds are not (at least for edible mushroom species) suitable to allow fruiting, at best they would get only a few mushroom, but we want great crops, right? :)
Seeds must necessarily be used to inoculate the final substrate: in this way they act as a nutritional supplement, and ensure a rapid colonization, that LC alone would not allow.
Best cereal (and most used) to use as spawn is rye, but also grain, sorghum, millet and barley will be fine. You can find all of them in wholesale seeds stores. You can also use for parakeets feeding, which often consists mainly of millet.
In this guide we will use rye.


First of all, you have to measure out the seeds, pouring them into jars filling them barely less than half. In fact, hydrated rye will double in volume, and will completely fill the jars. Lids should be prepared by following this guide.


 Pour the contents of all the cans in a pretty big pot...


... and fill it with hot water, until completely submerge the seeds. This phase has a double function: hydrate the seeds, until they reach the right level of humidity inside, and to germinate endospores, which could othersise withstand sterilization.


Close the pot with the lid and wait 24 hours. When uncovering again, you will notice that a light foam formed on the surface, and the water seems to fizz. This is because contaminant spores, contained in the seeds germinated, and bacteria begun to ferment. Drain the seeds (a colander is  just fine) and wash them for a while under cold water (to wash away any dirt). As you can see, the grains appear dramatically larger, because of the absorbed water.


At this point, if we had used the mile, which has much smaller grains , we should boil it for at least 15 minutes so that it absorbs more water and will not excessively dry out during mycelium colonization. But this operation with rye is not necessary, because grains are big enough to absorb the necessary water just with soaking. 
Then fill the jars, up to 1-2 cm to the lid.



Cover jars with an aluminum foil sheet, stopping it with a rubber band.


Now sterilize everything in a pressure cooker, for at least an hour (an hour and a half for safety) to 15 PSI. A solid content in fact require a longer time compared to liquids. In a hour and a half we will be sure that the center of each jar has reached 120 degrees for a period sufficient enough to kill all pests.


Let the pot cool up to ambient temperature (it takes several hours). Once cool,jars are ready to inoculate!



Grains get slightly smaller during sterilization, yet they retain a sufficient amount of humidity to be succesfully eaten by our mycelium.

Well, and this is done. In the next post we will see how to inoculate our nice jars :)

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