How To Prepare Mushroom Grain Spawn | Fundamentals


A reliable mushroom production relies heavily on high-quality spawn. As many mushroom farmers do not have access to high-quality spawn, they produce their own. But producing your own spawn is not an easy task, as many mushroom farmers still struggle even after years of running their farm.

In today’s video, I, therefore, do a literature review. Let’s get started.

There are commonly two different types of solid spawn – sawdust and grain. But we have to distinguish between generations 1, 2, and 3. According to Stamets, usually, generation 1 or G1 is grain. Followed by grain for G2 and grain or sawdust for G3.

I, therefore, talk for the rest of this video, only on the production of grain spawn.

In the analyzed papers, rye, wheat, sorghum, maize, rice, millet, barley, and Triticale were used as grain spawn material.

If you are not familiar with Triticale. Triticale is a hybrid of wheat and rye, which were developed to combine the yield potential and grain quality of wheat with the disease and environmental tolerance of rye.

Of all the papers I analyzed, 17 mentioned wheat grain as their main spawn material. Followed by 15 using sorghum grain and 8 which used millet grain.

29 of them used as their main supplement calcium carbonate to adjust the pH value. Calcium carbonate was applied in the range of 0.2% to 4%, with most of the papers (9) using 2%. One paper mentioned the use of oyster shells instead of calcium carbonate.

On the other side, 23 papers added calcium sulfate (gypsum) to the grains to prevent them from sticking. The range of gypsum was between 0.01% and 3%, with most papers (18) using between 1% and 2%. In one of the papers Epsom salt was used instead of gypsum.

Other mentioned supplements were wheat bran, rice bran, sawdust, oats or coffee husks in combination with coffee pulp. Overall, only 10 papers mentioned adding besides calcium carbonate and or gypsum other supplements to the mix.

When it comes to the treatment of the grains, 16 papers the grains were washed and soaked before adding supplements. The soaking time ranged from 20 minutes up to 36 hours. With 12 to 24 hours the most used soaking time.

When it comes to boiling, 20 papers mentioned it as a pre-treatment of the grains. The boiling time ranged from 10 minutes up to 40 minutes. Most of the papers (13) using a boiling time between 15 to 25 minutes.

After draining the excess water, the moisture content is between 49% and 65%, with most of the papers (16) mentioning 51 to 55%. The grains were either bagged (14 times) or put in glass jars or bottles (21 times).

The jars or bottles are filled between ½ and ¾ of the volume. The weight ranged from 66g up to 1,000g, with most of the papers used between 100g and 300g.

The main treatment in 36 papers was autoclaving with a typical temperature of 121°C. The time for the autoclaving ranged from 15 minutes to 180 minutes, with autoclaving of 60 minutes as the most often used time. Followed by 45 minutes.

In three papers, the grains were autoclaved twice with a pause of 1 to 2 days in between. One paper even mentioned a pause of 2 to 5 days in between the two autoclaving cycles.

This approach is similar to Tyndallization, where the product is heated up to 100°C and maintained for 30 minutes. This part of the cycle is called sterilization phase. The temperature is then dropped down to 37°C and hold for 12 hours. This part of the cycle is called germination phase. After 12 hours the product is heated up again to 100°C for 30 minutes.

The complete cycle is repeated 2-3 times until 72 hours are reached. During the germination phase the bacteria starts growing. In the sterilization phase these bacteria then will get killed. Tyndallization is, therefore, a good approach if you do not have access to an autoclave or a pressure cooker.

Give this video a thumbs up if you like this kind of deep dives and I will do more of it.

Talk to you in the next one.