Why pasteurize mushroom substrate?
Why should you pasteurize bulk substrate for mushroom cultivation? Pasteurization is a process that has been used for hundreds of years to destroy harmful germs in food. It is commonly known for its role in milk and juice production and was invented by the French chemist and microbiologist Louis Pasteur in 1864. Pasteurization only involves heat (no chemicals) to make foods safe for consumption.
By pasteurizing bulk substrates at 160-180°F, you can ensure that your mushrooms will have the best chance possible to survive. If you are using unpasteurized compost, contaminations are likely to happen, meaning unwanted organisms are growing in your substrate or your mushrooms don’t look good because they are weakened by pathogens. Pasteurizing it kills unwanted germs, while beneficial microorganisms, mainly bacteria, stay alive, inhabit the substrate and help guarding it against more aggressive microorganisms. This way the substrate is more resistant to contamination and can be inoculated with spawn without taking strict sterile precautions.
Some people go so far as to sterilize their substrate, killing all of the microorganisms in it. However, this also kills the beneficial bacteria and microbes, making it more prone to contaminations. Therefore, you would have to inoculate the bulk substrate in sterile conditions, for example under a flow hood or in a glove box and it would have to stay sterile until fully colonized. Since this is not very practical for large amounts of substrates, pasteurizing is usually the better option.
For those who wish to purchase their substrates pre pasteurized and ready to go, check out SubFarms.com