Pasteurization When Growing Mushrooms: Complete Guide (2023)

table of contents

Pasteurization is a crucial step in food preservation as it helps kill harmful bacteria that can cause foodborne illness. Although pasteurization is commonly associated with liquids such as milk,can also be applied to mushroom cultivation.

Most people sterilize their mushroom growing medium, but few know that pasteurization is different but achieves a similar goal.In fact, pasteurization is better for different substrates like straw.. It actually protects you instead of making you prone to contamination.

In this blog post, we'll take a closer look at the different methods of pasteurizing mushrooms, including hot water pasteurization, steam pasteurization, and ultraviolet (UV) pasteurization. We'll also discuss the pros and cons of each method, as well as factors to consider when choosing the right pasteurization method for your needs.

(Video) Sterilisation vs. Pasteurisation in Mushroom Cultivation I How To Grow Mushrooms I GroCycle

We will also cover the main differences between pasteurization and sterilization in mushroom cultivation.

What is the difference between sterilization and pasteurization in mushroom cultivation?

Pasteurization When Growing Mushrooms: Complete Guide (1)

Sterilization and pasteurization are two common methods used in mushroom cultivation to kill harmful bacteria and other pathogens. However, they are different processes with different characteristics.

What is sterilization in mushroom cultivation?

Sterilization is a more intensive process than pasteurization and its aim is tocompletely eliminate all living organisms in the substrate. This is done by exposing the substrate to high temperatures for an extended period of time, usually in an autoclave or pressure cooker. Sterilization is often used in commercial-scale mushroom growing operations as a way to ensure the highest level of quality and safety.

Read more about sterilizing mushroom growing substrates in this posthere.

What is pasteurization in mushroom cultivation?

Pasteurization is a gentler process that aims to reduce the number of harmful bacteria and other pathogens in the growing medium,but not remove them completely. This is done by exposing the substrate to moderate heat for a specified amount of time. The goal of pasteurization is to create a hospitable environment for fungal spores to grow and colonize, reducing the risk of contamination.

(Video) Growing Mushrooms, The Magic of Microwave Pasteurization

To use:keep this in mindpasteurization can be more difficult than sterilization, because it requires more specific heat and time than sterilization. With sterilization, you can simply leave the substrate on high heat for as long as you like. With pasteurization, time and heat are important as you are not trying to kill every microorganism present.

As we shared earlier, an example of a substrate that works best with pasteurization is actually straw. If you choose to use straw as a substrate for growing mushrooms, try pasteurizing it.

In conclusion, sterilization and pasteurization areof the different methods used in growing mushrooms, each with its own advantages and disadvantages. The choice between sterilization and pasteurization depends on the size and scope of the operation, as well as specific market requirements.

Different types of pasteurization in mushroom cultivation

Pasteurization is a critical step in the mushroom growing process as it helps to kill harmful bacteria and other pathogens in the growing medium. Here are the three main types of pasteurization for mushroom substrates:

  1. hot water pasteurization: this method consists of immersing the substrate in hot water for a certain time. The water temperature usually ranges from 140 to 160°F and is held for 60 minutes. This method is the simplest and most straightforward, making it a popular choice for small growers.
  2. steam pasteurization: This method uses steam to heat and sterilize the substrate. The substrate is placed in a steam chamber and exposed to steam for a certain period of time,usually around 60
  3. minutes at a high temperature of 160-180F. This method is faster and more effective than hot water pasteurization, but requires specialized equipment.
  4. pressure cooker pasteurization: this method uses a pressure cooker to sterilize the substrate. The pressure cooker is filled with the substrate and heated under pressure for a certain time. This method is simple, effective, and widely used, but it also requires specialized equipment.
Pasteurization When Growing Mushrooms: Complete Guide (2)

Note: Although sterilization and pasteurization can use the same equipment, the time and level of heating must be different. Sterilization is done at very high temperatures of over 200F for about 60-90 minutes.Pasteurization takes place at around 160-180F for just 60 minutes.

(Video) Home Growing Mushroom Tutorial - Cold Pasteurisation - Episode 2

Choosing the right pasteurization method depends on the size of your operation, the type of mushroom you are growing and the specific requirements of your market. Each method has its own advantages and disadvantages, so it's important to carefully consider all the factors involved before making a decision.

You can read more about pasteurization in mushroom cultivationhere.

What is the best pasteurization setting for my mushroom crop?

Choosing the right pasteurization setup for your mushroom growing operation depends on several factors, including your goals, the size of your operation and the type of mushrooms you are growing. Here are some important considerations to help you make the best decision:

  1. Objectives: What are your objectives for the mushroom growing operation? Do you want to maximize performance, minimize costs or prioritize security? Keep your goals in mind when choosing a pasteurization setting, as each method has its ownown strengths and weaknessesthat may or may not align with your goals.
  2. Operation Size: How big is your mushroom growing operation? Large scale operations may require more intensive setup such as sterilization to ensure maximum efficiency and productivity. Smaller operations may be better suited for a simpler setup, such ashot water pasteurization.
  3. Mushroom Type – Different types of mushrooms have different requirements to grow. Consider the specific requirements of the type of mushroom you are growing when choosing a pasteurization setup.Some mushroom substrates may be more sensitive to intense heatand require a milder process, such as hot water pasteurization.
  4. Orçamento: qual é o seu orçamento para a configuração da pasteurização? Alguns métodos, como esterilização e pasteurização a vapor, requerem equipamentos especializados que podemexpensive like pressure cookers. Consider your budget when making your choice, as well as the long-term cost savings that can be associated with different methods.

In conclusion, choosing the right pasteurization setup depends on several factors, including your goals, the size of your operation, the type of mushroom you are growing, your budget, and the availability of different methods. Consider each of these factors carefully when making your choice.

Why are sterilization and pasteurization important?

Sterilization and pasteurization in mushroom cultivation are ways that mushroom growers avoid contamination. Contamination is the greatest fear of mushroom growers. Contamination occurs when a substrate is not properly sterilized or pasteurized, leaving microorganisms such as mold present.

Once you leave your substrate with just your fungal spores to colonize it, mold can grow and outgrow your fungal spores. It will ruin your mushroom crop. Contamination can waste many hours of hard work if you don't take proper measures.

(Video) Bucket TEK Pasteurization: How to prep your Bulk Substrate!

As a general advice, once you notice contamination in your mushroom cultivation, you can no longer use this substrate. It must be thrown away for safety reasons, and there is no way around it. Contamination poses a health hazard as inhaling or consuming moldy substrate or moldy fungi is very risky to health.

Don't compromise or skip steps when it comes to sterilization or pasteurization in mushroom growing!


Pasteurization is different from sterilization in the practice of mushroom cultivation. In mushroom cultivation, pasteurization is a lighter version of sterilization, allowing safe microorganisms to remain while killing mold.

Pasteurization is recommended for certain types of mushroom substrates, such as straw. You must implement pasteurization when using certain types of substrates. Keep in mind that pasteurization can be more complicated than sterilization because it requires more careful planning and steps.

Back to Growmushrooms.orgCasa!


How long should I pasteurize mushroom substrate? ›

An effective pasteurization will eradicate harmful bacteria, nematodes, insects and fungi. In general a compost substrate temperature of 140° F for 4 hours is adequate for a complete pasteurization.

Does mushroom substrate need to be pasteurized? ›

Once that is ready, the substrate needs to be sterilized or pasteurized. This kills off any competing mold or bacteria and gives the desired species of mushroom the best chance at taking hold. If words like inoculation or mycelium seem overwhelming right now, our article How Do Mushrooms Grow?

How much spawn should I mix into a pasteurized substrate? ›

We recommended 1 lb of colonized grain spawn for each 5 lb Boomr Bag or Wood Lovr. Higher inoculation rates may improve your success. Be sure to mix your grain spawn thoroughly into your substrate.

How long do you pasteurize for? ›

Heat the milk to 63°C (150°F) for at least 30 minutes or 72°C (162°F) for at least 15 seconds.

Can mold spores survive pasteurization? ›

Heat-resistant bacteria and molds can survive the pasteurization conditions used in high-acid fruit juices.

What is the best temperature for pasteurization? ›

Slow pasteurization uses pasteurization temperatures for several minutes; e.g. typical temperature–time combinations are 63 to 65°C over 30 minutes or 75°C over 8 to 10 minutes. Rapid, high or flash pasteurization uses pasteurization temperatures of about 85 to 90°C or more for a time only in the order of seconds.

Can you pasteurize at 140 degrees? ›

But it is not just temp!

To pasteurize meat, USDA and my chart give us minimum temperatures, like 165°F for poultry and 145°F for fish.

How do you pasteurize temperature? ›

Pasteurization of milk, widely practiced in several countries, notably the United States, requires temperatures of about 63 °C (145 °F) maintained for 30 minutes or, alternatively, heating to a higher temperature, 72 °C (162 °F), and holding for 15 seconds (and yet higher temperatures for shorter periods of time).

What is the best way to pasteurize substrate? ›

Hot water pasteurisation is considered by many to be a more effective method of pasteurisation than cold water methods. Substrate should be fully submerged in water at a temperature above 80 degrees Celsius for 2 hours or more.

Do you need to pasteurize casing layer? ›

That being said, any casing layer is prone to some form of contamination, so it is generally a good idea to pasteurize it before applying to the top of the block. In order to pasteurize without changing the moisture content, I like to place it in a mushroom grow bag and simmer the mix in a pot for 45-60 minutes.

How do you tell if mushroom substrate is fully colonized? ›

Check on your bin daily to watch it colonize. You'll see white spots start to expand from each point of grain spawn. Over time they will completely cover the surface of the bulk substrate.

What is the best grain spawn for Cubensis? ›

Many different types of grains can be used for spawn – including wheat, rye, brown rice, white rice, wild bird seed and even popcorn. Without a doubt, however, the most common grain used for mushroom cultivation is Rye.

How can I speed up mycelium growth? ›

The higher the inoculation rate or amount of spawn added to the substrate, the faster the mycelium will grow through the substrate.

Does amount of spawn affect yield? ›

Spawn is the mushroom mycelium that has fully colonized a steam sterilized substrate that is used to 'seed' the final fruiting substrate. It serves as the planting material in mushroom cultivation (Romaine et al, 2007). The quantity of spawn used does not directly affect the yield of mushrooms (Quimio et al, 1990).

How much temperature and time is needed for pasteurization of milk? ›

In dairy industry pasteurization is designed to achieve at least a five-log reduction (or 99.999% killing) of the most heat-resistant non-sporulating pathogen likely to be present in cow milk (Coxiella burnettii); this requires heating every particle of the milk to 72°C for 15 s or an equivalent treatment.

What kills the pasteurization process? ›

Pasteurization is a process by which milk is heated to a specific temperature for a set period of time to kills harmful bacteria that can lead to diseases like as listeriosis, typhoid fever, tuberculosis, diphtheria and brucellosis.

Does pasteurization remove all bacteria? ›

Raw milk DOES NOT kill dangerous pathogens by itself. Pasteurization DOES NOT reduce milk's nutritional value. Pasteurization DOES NOT mean that it is safe to leave milk out of the refrigerator for extended time, particularly after it has been opened. Pasteurization DOES kill harmful bacteria.

Does pasteurization destroy spores? ›

Pasteurization is not a sterilization process; its purpose is to destroy all pathogenic microorganisms with the exception of bacterial spores.

What is the correct pasteurization protocol? ›

Pasteurization Type

The most common method of pasteurization in the United States today is High Temperature Short Time (HTST) pasteurization, which uses metal plates and hot water to raise milk temperatures to at least 161° F for not less than 15 seconds, followed by rapid cooling.

How long does it take to pasteurize at 180 degrees? ›

For this reason a scientist at the University of California developed the low-temperature pasteurization method for home picklers. By this method you don't boil your jars, you just immerse them in 180 to 185 F (82 to 85 C) water for 30 minutes.”

How long does pasteurization take at 150 degrees? ›

But pasteurization is a function of temperature and time. Cook your turkey breast to 150 degrees, and so long as it rests there for at least 3.7 minutes, it will have the exact same level of bacterial reduction, and come out far, far juicier in the process.

How long to pasteurize at 130 degrees? ›

According the USDA as of 2017, the method used commercially to pasteurize eggs is immersing eggs in hot water between 130-140°F for one hour.

How long does pasteurization take at 145? ›

Milk can be pasteurized by heating to 145 degrees F (62.8 degrees C) for half an hour or 161 degrees F (72 degrees C) for 15 seconds. Other combinations of time and temperature can do the same thing, just like when we cook foods.

What temperature is considered as danger zone in pasteurization? ›

The "Danger Zone" (40 °F-140 °F)

Bacteria grow most rapidly in the range of temperatures between 40 ° and 140 °F, doubling in number in as little as 20 minutes.

What are the two methods of pasteurization? ›

When it comes to pasteurizing dairy products such as milk and cream, two of the most common types are vat pasteurization and HTST pasteurization.

How do you calculate pasteurization time? ›

It is defined by an equation : PU = (time in minutes) x 1.393 exp(T-60), where T is the temperature in Celsius. Hence if you want 50 PU, you would need less than 2 minutes at 70C, or 10 minutes at 65C, or 50 minutes at 60C, or 250 minutes at 55C, or some combination that would yield the total desired.

What does 100% pasteurized mean? ›

Pasteurized juices have been heated to high temperatures for a short time in order to kill any bacteria or other microorganisms that may be present.

What bacteria can survive pasteurization? ›

Bacillus spp. and Clostridium spp. are the organisms most likely to survive pasteurization as a consequence of their ability to form heat-resistant endospores.

What temperature should mushroom substrate be sterilized at? ›

Temperature. The temperature required by most Mushroom growers is 121°C (250°F) requiring 15psi. Some equipment can go higher, so requiring less time. Note: at altitude, the water will boil at a lower temperature.

How do you cold pasteurize mushroom substrate? ›

It's called Cold Water Lime Pasteurization, and it's a cheap and effective low-tech way to prepare substrates for growing mushrooms. The process is simple. You basically just soak straw for 12-24 hours in a bath of cold water that has been treated with hydrated lime.

Does everything need to be pasteurized? ›

Although pasteurization is a common practice that makes food safer to eat and extends shelf life, not all foods can be pasteurized. Plus, pasteurized foods are still at some risk of contamination from harmful microbes ( 1 , 2 ).

Is pasteurization really necessary? ›

Yes. Even healthy animals may carry germs that can contaminate milk. Small numbers of bacteria can multiply and grow in milk from the time it is collected until the time a person drinks it. If the milk is not pasteurized to kill germs, people who drink it can get sick.

What does basic pasteurization require? ›

Batch pasteurization involves heating every particle of milk in a large tank or vat to a minimum of 145° F for a minimum of 30 minutes. Examples of continuous flow pasteurization are: High-Temperature, Short-Time (HSTS) pasteurization: requires that the milk be held at a minimum of 161°F for 15 seconds.

How long does it take for mycelium to fully colonize? ›

Colonization of Mushroom Substrate

The picture on the right highlights the colonization stage of mycelium, this process will often take 20 – 30 days depending on environmental temperature.

How long does it take to fully colonize bulk substrate? ›

It will take approximately 5-10 days for the substrate to completely colonize with mycelium (you will be able to tell if it has completed colonization when the substrate has turned completely white).

What does contaminated mycelium look like? ›

If you spot green, blue, grey, or black patches on or in your fruiting box, your culture is most likely contaminated. Do keep in mind, however, that small blue stains in the mycelium may just be bruising and not mould. Especially where the rye presses the mycelium against the grow box, you may see some blue spots.

How can I make mycelium stronger? ›

Yeast extract is good for fungi and might make them stronger as it helps them grow.

What is the best medium to grow mycelium? ›

Using Hardwood Sawdust and Chips

The fine sawdust is typically mixed with wood chips, which seems to allow for faster colonization of the substrate and provide a better structure for the mycelium to take hold. Commonly used hardwoods are oak, maple, beech, and hickory- or a mix of multiple species.

What humidity does mycelium grow best? ›

It is important to keep the temperature stable, otherwise mycelium can overheat resulting in the death of the mushroom. Humidity: Mushrooms need constant, high humidity to develop properly. This requires a humidifier and a means of keeping a constant Relative Humidity (RH) between 80-90%.

What temperature is best for mycelium? ›

Mycelium grew best during spawn-running when the temperature was kept at 75° F. (23·9° C.) During pre-cropping a temperature of 65° F. (18·3° C.)

Does music help mycelium grow? ›

The results showed that the sound increased the mycelium growth of all the six mushrooms by 10.2%21%accelerated their fruiting, advanced the body fruiting harvest time by 1-5 days and extended the picking period by about 3-8 days.

What stimulates mushroom growth? ›

Temperature is one of the critical factors for fruiting body induction in basidiomycetes. Especially, down shift of temperature stimulates fruiting body induction in many mushroom species.

What is the best mushroom spawn ratio? ›

Mix grain spawn throughout at a ratio of 1:5 to 1:10 and load into your fruiting vessel.

What is a good quality spawn? ›

CHARACTERS OF GOOD SPAWN : There should be proper coating of the mycelium around every grain used as substrate for spawn. The growth of the mycelium in the spawn bottles should not be cottony or fluffy type but it should be strandy . The growth of fresh spawn is more or less white.

What temperature should a spawn run be? ›

The ideal temperature for a spawn run depends on the type of mushroom, but it is generally between 23 and 28 Celsius (73 and 82 Fahrenheit).

How long do I sterilize mushroom substrate? ›

Submerging the substrate in hot water for at least one or two hours is one approach to pasteurise it. Pasteurisation is sufficient for most enterprises to grow mushrooms with minimum risk of contamination.

How long should you sterilize substrate? ›

When sterilizing your substrate, longer and hotter is NOT better! A temperature of 121°C or 250°F will do the job. Just be sure the complete mass of substrate reaches that temperature for 30 minutes.

How long does mushroom substrate sterilization take? ›

Generally, sterilizing substrate blocks in a pressure cooker at 250°F (121°C) takes anywhere from 1 to 4 hours. The minimum sterilization time for small blocks of substrate is one hour, and for large blocks, 3 to 4 hours. If you leave the blocks for too long, there's a danger of over-sterilization.

How long does it take to pasteurize soil? ›

Potting media mixed by home gardeners should be pasteurized to kill weed seeds, soil-borne insects, and pathogens. Pasteurization destroys most organisms and is done by applying heat until the soil reaches 180oF (82oC) for 30 minutes.

How do you pasteurize large amounts of substrate? ›

Hot water pasteurisation is considered by many to be a more effective method of pasteurisation than cold water methods. Substrate should be fully submerged in water at a temperature above 80 degrees Celsius for 2 hours or more.

What temperature should mushroom substrate be sterilized? ›

Temperature. The temperature required by most Mushroom growers is 121°C (250°F) requiring 15psi. Some equipment can go higher, so requiring less time. Note: at altitude, the water will boil at a lower temperature.

Do you seal mushroom bags before sterilizing? ›

There is no need to seal the bag before sterilization. Any air drawn into the bag during cool down will be passed first through this tyvek filter. Simply pull the tyvek sleeve out after the bag cools off, and right before inoculating your bag.

How do you know if a substrate is contaminated? ›

In areas where substrate presses against glass and condensation is present brown-yellow slimy rings are often present around the grains. The material will also look sludgy and thick, bacterial contamination often accompanies an odor of fermentation or decay. Spongey or Soft: Your Mycelium block is soft and squishy.

What happens if you don't sterilize substrate? ›

Sterilization of the substrate is one of the critical steps when it comes to mushroom cultivation. Without a good sterilized substrate, the level of contamination within the substrate is too high for the mycelium to grow. This, therefore, leads to low yield or even worse to a total loss.

What is the best sterilizer for mycology? ›

All-American Pressure Sterilizers are the gold standard in sterilization for mushroom growers. Unlike regular pressure cookers, they feature a stopcock that prevents steam from escaping once ideal temperatures have been achieved.

How long does Pasteurised substrate last? ›

Pasteurized Casing: Leave in original packaging. Store your casing in a cool and dry location. Casing can keep for up to 4 months in these conditions. There will be no need to rehydrated or sterilize the products a second time.

How many times can you reuse mushroom substrate? ›

Mushroom kits are not reusable, but most of them produce at least 2 harvests' worth of mushrooms. This means that you can get multiple harvests out of a single kit before needing to replace it. After a mushroom block stops producing, you can bury it to get some more flushes from the soil surface!

How many days after mycelium is inoculation? ›

Once inoculated, the mycelium takes upwards of 10 days to jump off the spawn into the substrate.

What is the ideal temperature for pasteurization? ›

Slow pasteurization uses pasteurization temperatures for several minutes; e.g. typical temperature–time combinations are 63 to 65°C over 30 minutes or 75°C over 8 to 10 minutes. Rapid, high or flash pasteurization uses pasteurization temperatures of about 85 to 90°C or more for a time only in the order of seconds.

Can you pasteurize without heat? ›

As the name implies, the cold pasteurization technique does not make use of heat to reduce the microbial load. Instead, microporous membrane filters are used to retain the majority of bacteria and yeasts. In this respect, the technique is similar to any other pasteurization process.


1. How to Pasteurise Coco Coir for Mushroom Substrate - easy
(Blue Moon Mycology)
2. Cold Water Lime Pasteurization For Growing Mushrooms
(FreshCap Mushrooms)
3. How to Pasteurise Mushroom Substrate (5 Easiest Methods)
4. Home Mushroom Growing Tutorial - Heat Pasteurisation
(Aussie Mushroom Supplies)
5. Easy 'fool proof' Substrate Pasteurization! Mushroom Oven Tek
6. Guide of How to Pasteurize & Spawning the Fruiting Bags of Mushrooms
(Garden of Hope)


Top Articles
Latest Posts
Article information

Author: Jerrold Considine

Last Updated: 06/17/2023

Views: 5924

Rating: 4.8 / 5 (78 voted)

Reviews: 85% of readers found this page helpful

Author information

Name: Jerrold Considine

Birthday: 1993-11-03

Address: Suite 447 3463 Marybelle Circles, New Marlin, AL 20765

Phone: +5816749283868

Job: Sales Executive

Hobby: Air sports, Sand art, Electronics, LARPing, Baseball, Book restoration, Puzzles

Introduction: My name is Jerrold Considine, I am a combative, cheerful, encouraging, happy, enthusiastic, funny, kind person who loves writing and wants to share my knowledge and understanding with you.