Phase II Pasteurization & Conditioning


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Phase II is the second step in the substrate preparation process.

The first objective of Phase II is to pasteurize the composted substrate. 
The composted substrate is pasteurized to reduce or eliminate bad microbes such as insects, other fungi, and bacteria.  This is not a complete sterilization but a selective killing of pests that will compete for food or directly attack the mushroom.  At the same time, this process minimizes the loss of good microbes.

The second objective of Phase II is to complete the composting process.
Completing the composting process means eliminating all remaining simple soluble sugars and gaseous and soluble ammonia created during Phase I composting.  Since ammonia is toxic to the mushroom mycelium, it must be converted into food the mushroom can use.  The good microbes in Phase II convert toxic ammonia substances into protein—specific food for the mushrooms so that what little ammonia is left, will not inhibit mushroom spawn growth.  Most of this conversion of ammonia and carbohydrates is accomplished by the growth of the microbes in the substrate.  These microbes are very efficient in using Phase I substrate products, such as ammonia, as one of their main sources of food.  The ammonia is incorporated as mostly protein into their bodies or cells. Eventually the mushroom uses these packets of nutrients as food.

Pasteurization & Conditioning

The substrate transported from the Phase I site is unloaded directly into a large hopper which transfers it to an overhead conveyor.


Pasteurization & Conditioning

Through a series of overhead conveyors, the substrate is then transferred to a “Cassette Conveyor” which delivers, in an evenly distributed level, the substrate into stainless steel lined tunnels.  These tunnels are climate controlled to expose the substrate to the necessary pasteurization and conditioning temperatures.

Effective pasteurization will eradicate harmful bacteria, insects, fungi, and any other competing elements.  This is done by raising the temperature of both air and substrate in the tunnels to 60 degrees Celsius (140 degrees F.) for at least two hours.

Effective conditioning of the substrate involves reducing the temperature of the air and substrate to a range where the desirable microbes thrive.  After pasteurization, temperatures are gradually reduced to between 47 to 49 degrees Celsius (120-128 degrees F),  The more ammonia-utilizing microbes grow best in this range and the longer the substrate is maintained in this temperature window the faster the ammonia will be converted into mushroom food.

The complete Phase II operation takes 5-6 days.  At the end of this operation the substrate is cooled down to 26 degrees Celsius and then transferred (by way of conveyors) to an incubation tunnel.

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