Laura Smith
Autoclaving is a crucial step in mushroom cultivation, and it involves subjecting mushroom bags to high temperatures for sterilisation. The process is typically done in a pressure canner at 15 PSI, reaching temperatures of about 250°F for extended periods. Autoclave bags are made of heat-resistant materials like polypropylene, with varying thicknesses and filter patch sizes, to accommodate different substrates and ensure ample gas exchange during colonisation. Proper techniques, such as avoiding direct contact with the autoclave's base and allowing it to cool and depressurise before opening, are essential to prevent bag damage and rupture.
| Characteristics | Values |
|---|---|
| Material | Polypropylene |
| Thickness | 60-65 microns |
| Filter | 0.2-micron filter disc |
| Size | 8" x 4.75" x 18" to 10" x 5.5" x 24" |
| Capacity | 6 lbs |
| Temperature | 250 °F |
| Safety | Keep away from metal sides of equipment, avoid sudden pressure changes, and never leave unattended |
Explore related products
What You'll Learn
Choosing the right bag
When choosing the right bag for autoclaving mushrooms, there are several factors to consider. Firstly, you need to decide whether you need to sterilize your substrate or if pasteurization will suffice. If sterilization is required, you will need autoclavable bags made from polypropylene, which can withstand high temperatures of around 250°F (121-132 °C) in an autoclave, sterilizer, or pressure cooker. Polypropylene bags typically range in thickness from 2.2 to 6 mil (or 56 to 150 microns). Thicker bags are less likely to tear but are more expensive. If you are pasteurizing, any sturdy plastic bag with holes for air exchange will do.
The size of the bag is another important consideration. Choose a size that fits your available space and the number of mushrooms you want to grow. If you are sterilizing, ensure the bag fits inside your pressure cooker or autoclave. The bag should also be large enough to accommodate the amount of grain or sawdust you plan to use.
The type of filter is also crucial. Filters come in different sizes, and the ideal size depends on the mushroom species and whether you are using the bag for spawn or substrate. Larger pore sizes facilitate more air exchange but increase the risk of competitor organisms entering. Therefore, larger filters are better suited for faster-growing species to minimize the risk of contamination.
Some bags have filter patches, which are small sections of the bag with filters. Others, like zipper filter bags, have filter strips covering the entire length of the bag for optimal air exchange. Still, others have self-healing injection ports, reducing the chances of contamination. Additionally, some growers are exploring the use of biodegradable mushroom bags, although these are not yet commercially available.
When selecting a bag, consider the specific requirements of the mushroom species you plan to grow, the type of substrate, and the quantity. Reading reviews from other mushroom growers can also provide valuable insights into the effectiveness and durability of different bags.
The Art of Slicing Chanterelle Mushrooms
You may want to see also
Preparing the bags
When preparing mushroom bags for autoclaving, it is important to select the right type of bag. Mushroom grow bags are typically gusseted autoclavable polypropylene filter patch bags. Gusseted refers to the way the bag is folded, with the sides folded flat towards the inside, allowing the bag to fold small and flat, but also open up wide to accommodate a large volume of grain or sawdust. This shape also comes in handy during sterilisation, as a filter can be slipped between the gussets to prevent contamination from the air that enters the bag during the post-sterilisation cooldown.
Autoclavable simply means that the bag can withstand the high temperatures of an autoclave, or steriliser. An autoclave typically operates at 15PSI, reaching temperatures of about 250°F, sometimes for hours at a time. Therefore, it is important to select bags that are designed to withstand high temperatures during sterilisation. Bags made of polypropylene plastic are ideal, with some bags able to withstand temperatures of up to 275°F.
When preparing the bags, it is important to ensure that the inside walls of the bag are clean before inserting the filter. A small cloth filter can be used, with Tyvek being a good option. You can also use cut-up pieces of a painter's suit, which can be purchased at any hardware store or on Amazon. The filter should be placed between the gussets above the substrate.
Once the filter is in place, simply fold the bag over a couple of times and load it into the steriliser. There is no need to seal the bag before sterilisation. Make sure that the water level in the pressure cooker is lower than the height of the filter to avoid getting the bags soaked. Additionally, be careful not to spill any substrate on the upper regions of the bag. If you do, wipe it clean.
Mushrooms: Are They Vegetables or Something Else?
You may want to see also
Sterilising the bags
Firstly, it is important to select the right type of bag. Mushroom grow bags are typically made of autoclavable polypropylene with a filter patch. This material can withstand high temperatures and pressure during sterilisation. The bags should be thick enough to be durable, but also allow for ample gas exchange through the filter. Make sure the bags are specifically designed for high temperatures, as some plastic bags can be damaged by prolonged direct contact with the base of an autoclave.
Before filling the bags, ensure they are clean and dry. It is recommended to fill the bags halfway and then fold them over twice. This ensures that the filter is not obstructed and prevents any substrate from spilling onto the upper regions of the bag. If there is any spillage, be sure to wipe it clean before proceeding.
When using an autoclave or pressure cooker, always allow it to cool down and depressurise before opening and removing the bags. Any sudden change in pressure can cause the bags to rupture or burst. Additionally, never leave the bags unattended in the autoclave or pressure cooker, and keep them away from the metal sides of the equipment to avoid damage.
To prevent contamination during the sterilisation process, it is recommended to use a small cloth filter, such as Tyvek, or even pieces of a painter's suit. Place the filter between the gussets of the bag above the substrate. Ensure the inside walls of the bag are clean before inserting the filter. Then, simply fold the bag as instructed before and load it into the steriliser. There is no need to seal the bag before sterilisation.
By following these steps, you can effectively sterilise mushroom grow bags, creating an optimal environment for mushroom cultivation.
Shiitake Mushrooms: To Wash or Not to Wash?
You may want to see also
Explore related products
Cooling the bags
Cooling the mushroom bags is a critical step in the autoclaving process. It ensures that the bags do not rupture or burst due to sudden pressure changes. Here are the detailed steps and considerations for this stage:
Firstly, it is essential to allow the autoclave to cool down before opening it. This natural cooling process should be slow and gradual to maintain a consistent internal pressure. The specific duration may vary, but it typically ranges from 10 minutes to over 30 minutes, depending on the contents inside.
During the cooling phase, it is crucial to monitor the temperature of both the autoclave and the bags. The goal is to prevent the autoclave from cooling off faster than the bags. If the autoclave's internal temperature drops too quickly, it can cause the steam inside the bags to condense rapidly, leading to bag explosion. Therefore, a slow and controlled cooling process is vital to avoid this issue.
To facilitate a gradual cool-down, you can utilize the exhaust cycle of the autoclave. By setting an exhaust time, you allow the autoclave to cool down in a controlled manner while maintaining the necessary pressure inside the bags. This helps to prevent sudden pressure changes that could damage the bags or affect the sterilization process's effectiveness.
Additionally, it is worth noting that a little evaporation can contribute to significant cooling. This natural process can aid in gradually lowering the temperature inside the autoclave and the bags, further reducing the risk of sudden pressure changes that could cause bag rupture.
Lastly, it is important to remember that the bags should not be sealed until after inoculation, not before sterilization. Allowing the bags to cool first is essential to prevent the creation of a vacuum, which could negatively impact the cultivation process. By following these detailed instructions, you can ensure the successful cooling of your mushroom bags after autoclaving.
Mushroom Mulch: Acidic or Alkaline?
You may want to see also
Storing the bags
Storing autoclaved mushroom bags requires careful attention to ensure the bags remain uncontaminated. After autoclaving, it is important to let the bags cool down to room temperature before inoculating with mushroom spawn. The residual heat in the bags can kill the mushroom mycelium, so it is recommended to let the bags rest for several hours or overnight.
Once the bags have cooled, they should be stored in a clean, dust-free environment to prevent contamination. The ideal temperature for storage is between 50-60°F (10-15°C), with a humidity level of around 70-80%. It is crucial to avoid direct sunlight, as this can cause overheating and promote bacterial growth. Additionally, the storage area should be dark and well-ventilated to maintain optimal conditions for the bags.
To further reduce the risk of contamination, it is recommended to wipe down the outside of the bags with a damp cloth before storing them. This removes any dirt or debris that may have accumulated during the autoclaving process. It is important not to soak the bags in water, as this can lead to contamination. Instead, a gentle wipe-down is sufficient to ensure the bags are clean and ready for storage.
Proper storage of autoclaved mushroom bags is critical to maintain the quality of the bags and prevent any unwanted bacterial or fungal growth. By following these steps, you can ensure that your mushroom bags are stored correctly and are ready for future use.
Cleaning Button Mushrooms: To Wash or Not?
You may want to see also
Frequently asked questions
Mushroom grow bags are gusseted autoclavable polypropylene filter patch bags. The gusseted design refers to the way the bag is folded, with the sides folded flat towards the inside. This allows the bag to fold small and lay flat, but also be able to open wide to accept grain or sawdust.
Autoclaving is a form of sterilisation. Autoclaving mushroom bags prevents contamination from the air that enters the bag during the post-sterilisation cool-down.
Before sterilisation, a small cloth filter should be inserted between the bag's gussets. Tyvek is a good material to use for this. The inside walls of the bag should be clean before inserting the filter. Then, fold the bag over a couple of times and load it into the steriliser.
Always allow the autoclave to cool down and depressurise before opening it to remove the bags. Any sudden change in pressure will cause the bags to rupture or burst.
