What is the Pasteurization of Substrate?
If you are thinking about buying mushroom substrate or are in the process of making your own mushroom substrate, you may be wondering what substrate pasteurization is and how does it differ from sterilization?
Pasteurization of substrate is a process of treating the growth medium or substrate for mushroom cultivation to eliminate any unwanted bacteria, viruses, or other organisms that may compete with or harm the mushrooms. Pasteurization is different from sterilization, which involves completely killing all microorganisms, both beneficial and harmful.
The pasteurization process is intended to kill unwanted molds, fungi, and bacteria living in the substrate material that may compete with your growing mycelium. Any remaining living microbes have a symbiotic relationship with growing mycelium and help to ward off harmful contaminates.
In mushroom cultivation, pasteurization of substrate is typically achieved by heating the growth medium to a specific temperature for a specific period of time. This temperature and time combination is designed to kill off unwanted microorganisms while preserving beneficial ones. The exact temperature and duration of pasteurization will depend on the specific growth medium and the type of mushroom being cultivated.
For example, in the cultivation of oyster mushrooms, straw is commonly used as the growth medium. The straw is first soaked in water and then heated to a temperature of around 70-80°C (158-176°F) for 1-2 hours. This process kills off any unwanted microorganisms in the straw while preserving beneficial microorganisms, such as fungi that help break down the straw and provide nutrients to the mushroom mycelium. The main difference between pasteurization and sterilization is what microbes (bacteria, fungi, molds, etc..) are left living in the substrate.
Overall, pasteurization of substrate is an important step in mushroom cultivation, as it helps to ensure that the mushrooms grow in a healthy environment free from unwanted competition and harmful pathogens.
