February 21, 2024
Austin, Texas, USA
Health & Fitness

How To Pasteurize Mushroom Substrate

Substrate pasteurization is an essential process of you wants to cultivate mushrooms at home. Using substrate for mushroom cultivation is synonymous to using soil to grow different species of plants. The type of substrate you choose also determines to what extent your mushroom cultivation will be successful.

Oftentimes, people who are just starting out with mushroom cultivation ask how to pasteurize mushroom substrate correctly, not to worry, we’ve got you covered! In this article, we’ll take you through the steps for how to pasteurize mushroom substrate. But first, let’s take a look at what substrate and pasteurization means.

What is Mushroom Substrate?

A mushroom substrate refers to a material that gives room for the vegetative part of a fungus comprising hyphae to grow – this vegetative part is called mushroom mycelium.By providing nutrition, moisture, and energy that mushrooms require to grow. Mushroom substrate play the role of a fertile ground for mushrooms.

There are different types of mushroom substrates that growers use to cultivate mushroom at home. The choice of the substrate is also dependent on the specie of mushroom being cultivated as different species grow on different substrates.

What Pasteurization means.

Pasteurization is a process of partially sterilizing a product or material such as mushroom substrate, milk, wine and others. This process improves the quality of the product and makes it safe for use.

Preparing Substrate and Substrate Pasteurization

Before you can think of growing your mushrooms in a substrate or even pasteurizing it, the substrate has to be prepared first. There are different methods of preparing a substrate depending on the type you choose. Straw is the most popular of them and this could be cereal straws excluding hay. To prepare the substrate, you need a mix of water and other additional nutrients if you choose to add them. Following the preparation of the substrate, pasteurization of same is the next step.

Substrate pasteurization is a process of reducing the number of contaminates or microscopic elements in a substrate. This process kills off unwanted bacteria or fungi or even mold in the substrate, making it a sterile ground for mushrooms to grow. 

 Preparing Straw

We have pointed out earlier in the article that straw is the commonest mushroom substrate widely used by farmers or growers. The popular question however, is how to prepare straw. It is important to know that there are different methods of preparing straw and the popular ones are;

  • Heat pasteurization
  • Cold fermentation
  • Lime bath treatment
  • Chemical treatment such as the use of peroxide.

Heat Pasteurization

It is vital to know that the ideal method for straw is pasteurization and not sterilization. If you decide to use the heat pasteurization method, the procedure includes cutting the straw into small lengths of between 3 to 4 inches – a shredder is effective for this purpose.

Once you cut the straw, pasteurize inside by putting them in pillow case, laundry bag, nylon mesh or other similar items, then put inside water and heat up for one hour between 160-170 degrees F. If you are pasteurizing your straw outdoor, use a big gallon or drum, wire mesh basket and pasteurize in a large quantity.

Allow the straws to cool off and drain them appropriately before you inoculate with grain spawn.

Cold Fermentation

To use this method, you need to submerge your bags of straw under water for a minimum of seven days and maximum of 10 days. This duration will allow for fermentation to take place and remove molds, contaminates and microorganisms present in the straw. If you are doing cold fermentation for a larger quantity of straw, leave them underneath water for about two weeks. Just like you do when you pasteurize in heat, you need to drain the straws and ensure you wear a glove. Put them on a clean surface afterwards and they are ready for inoculation.

Lime Bath Treatment

To use this method, you need to prepare a gallon drum, clean water, hydrated lime or calcium hydroxide or alternative quicklime otherwise known as calcium oxide and a stirring tool. First, you need to fill the gallon drum with clean water, and then add the treatment items you’ve prepared. Submerge the straws in the gallon water filled with hydrated lime or quicklime and leave for 2 to 4 hours. Drain the straws afterwards and inoculate with spawn.

Chemical Treatment

Peroxide is the common chemical people use for straw pasteurization. To use this method, first soak the straw for a while and drain, rinse with clean water, then soak in a peroxide solution for 24 hours. Drain and rise with fresh water twice, then you can inoculate with spawn.

Conclusion A good mushroom substrate must have sufficient nutrients to grow your mushroom properly. Some of the nutrients include magnesium, potassium, calcium, sulphur, and phosphorus. A good substrate should also be slightly acidic and have a small percentage of nitrogen.

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