mushroom sterilization

1. Method of sterilization of
substrates for Oyster
cultivation.
M

2. Prepared by:
Mayur Baria 4011120015
Harsh Nayi 4011120017
Submitted to:
Dr. Sneha Mistry

3. Introduction
● Oyster mushrooms, the common name for the species Pleurotus
ostreatus.
● They're also known as pearl oyster mushrooms or tree oyster
mushrooms.
● Oyster mushrooms are eaten in a variety of cuisines and are
especially popular in Chinese, Japanese, and Korean cooking.
● The mushrooms typically have broad, thin, oyster- or fan-shaped
caps and are white, gray, or tan, with gills lining the underside.
● The caps are sometimes frilly-edged and can be found in clusters
of small mushrooms or individually as larger mushrooms.
● Oyster mushrooms are more expensive than white button
mushrooms.

4. Oyster
mushroom
01

5. What Is
Sterilization?
● Sterilization of mushroom substrates is
a method of preparing substrates using
a combination of steam, time,
temperature and pressure to kill living
organisms and spores.
● To sterilize a substrate, you need
temperatures higher than 250°F (121°C)
for at least 2 hours.
● Most mushroom growers will need 15
PSI of pressure to increase the
temperature of the steam to 250°F
(121°C).

6. Does Mushroom
Substrate Need to
Be Sterilized?
● If you want more nutrient from
substrates, you must go for sterilization.
● The more nutrients a substrate contains,
the greater the chances of
contamination.
● Moist, nutrient-rich substrates are not
only appealing to mushroom mycelium.
Other organisms, like mold and
bacteria, also enjoy them and often
grow faster than mushroom mycelium.
● Sterilizing a substrate kills all living and
dormant organisms and fungal spores
and gives your mushroom mycelium the
best possible head start.

7. What’s the Difference Between
Sterilizing and Pasteurizing
Mushroom Substrate?
● The main difference between the two is
that sterilization aims to kill all potential
contaminants, while pasteurization
eliminates most, but not all, competing
organisms.
● There are several pasteurization
methods that reduce the competing
organisms in less nutritious substrates,
like straw and sugarcane bagasse,
enough to give fast-growing mushroom
species an advantage.

8. 02
Pasteurizing
Mushroom

9. Sterilize Mushroom Substrate With a
Pressure Cooker
Metal cooking
rack
Water
A pressure
cooker
Jars or bags of
prepared
substrate
01
03
02
04
To sterilize a substrate with a pressure cooker, you’ll need the following items:

10. Step 1: Check Your Pressure Cooker
Step 2:Put Your Substrate in the
Pressure Cooker
Step 3:Add Adequate Water

11. Step 4: Close the Lid and Turn up
the Heat
Step 5:Monitor Pressure and Sterilize
the Substrate
Step 6: Turn Off the Heat and Leave
to Cool

12. How Do You Sterilize a Mushroom
Substrate Without a Pressure
Cooker?
● Barrel steam sterilizers are ideal for this
and popular with small mushroom farmers
who don’t have the funds for an autoclave.
● This article from Archer’s mushrooms
shows you how to build a barrel
sterilizer step by step.
● But you can also buy ready-to-use barrel
steam sterilizers online, like
these mushroom substrate steamers from
Bubba’s barrels.

13. ● When using a steam sterilizer, the substrate is super pasteurized rather than
sterilized.
● Super pasteurization is also known as atmospheric sterilization and involves
keeping the substrate as close to 212°F (100°C) as possible for long periods.
● When using a barrel steam sterilizer, you’ll need to keep the substrate between
194 and 212°F (90 and 100°C) for up to 18 hours.
● It takes much longer, but the results are almost identical to classic sterilization
and suitable for most mushroom species.
Conti…

14. ● You cannot sterilize mushroom substrate in the
oven, but you can pasteurize it.
● This method is sometimes used for small
quantities of substrate or casing material.
● One of the challenges when using an oven to
pasteurize mushroom substrate at 250°F
(121°C) for 30 minutes is that you can’t use
bags.
Sterilize Mushroom Substrate in an
Oven

15. Conti…
• This means that as soon as the substrate cools
down, it’s often exposed to airborne
contaminants.
• The oven’s dry heat also dries out the substrate
and may burn it, reducing the nutrients available
for the mycelium.
• If the substrate dries out too much while in the
oven, you’ll have to rehydrate it using distilled
water to help prevent contamination.

16. ● As with the oven, you can pasteurize small
quantities of mushroom substrate in the
microwave.
● But it’s not a reliable way to sterilize substrate
as it doesn’t kill all fungal spores.
● Microwaves work by causing the water
molecules in substances to vibrate, creating
heat that cooks or heats the food.
Sterilize Mushroom Substrate in a
Microwave

17. Conti…
• This means a microwave can’t reach
temperatures much higher than boiling point
212°F (100°C).
• Fungal spores don’t contain much water, making
them difficult to heat.
• And steaming alone will not create temperatures
high enough to kill them.
• But, you can use a microwave steamer to
pasteurize small quantities of substrate and
reduce the number of competitors.

18. Sterilize by autoclave
● Autoclaves operate at high
temperature and pressure in
order to kill microorganisms
and spores.
● They are used to
decontaminate certain
biological waste and sterilize
media, instruments and lab
ware and mushroom bag.

19. Sterilization by chemical
● Benzimidazole fungicides, viz, benomyl,
carbendazim, and thiophanate-methyl, are the most
utilized fungicide for substrate sterilization of
mushroom.
● The sterilization process is 8 hours at a
temperature of 70–95 oC.

20. THANK
YOU