Instant Pot Tek: Pasteurization & More

The Instant Pot is a versatile tool, perfect for pasteurization and other key tasks in mushroom cultivation. Its warm function is ideal for maintaining pasteurization temperatures, and with its multiple settings, you can handle agar, liquid cultures (LC), and even grain prep with ease.

Pasteurization: Using the Warm Function

The Warm function holds food (or your substrate) at about 165°F, ideal for pasteurization. Here’s how to pasteurize your substrate using quart jars:

Method 1 - Using Quart Jars:

  1. Prepare Substrate: Follow your preferred substrate prep method (coco coir, straw, etc.). Ensure the moisture content is correct.

  2. Load Jars: Fill your quart jars with the prepared substrate, not too tightly packed. Place the jar lids upside down and don’t over-tighten.

  3. Set Up Instant Pot: Place jars in the Instant Pot, fill with hot water up to the jar's neck. The jars will float—this is normal. Close the lid.

  4. Activate Warm Function: Press the Warm button and let it run. The water will reach and maintain pasteurization temperature (around 165°F). Internal temperature reaches pasteurization in about 3 hours.

Note: Avoid the yogurt setting—it holds at 110°F, not suitable for pasteurization.

Agar Prep in the Instant Pot

  1. Mix Agar: Add 100 ml cold water to your agar bottle. Mix in 10g agar and your nutrient source (e.g., 15g LME). Stir well and add hot water to make 500 ml.

  2. Set Up Pot: Place the agar bottles in the Instant Pot. Add hot water up to the level of the agar in the bottles to prevent them from tipping.

  3. Manual Cycle: Set the Instant Pot on Manual for 20 minutes. Walk away.

  4. Keep Warm: If needed, leave the Warm function on to keep the agar at around 160°F until ready to pour. When the agar cools to about 120°F, pour into plates.

Liquid Culture (LC) Prep in the Instant Pot

  1. Mix LC: Add 500 ml cool water to a jar. Stir in your nutrient source (e.g., 15g LME) and break up any clumps.

  2. Set Up Pot: Place the jar in the Instant Pot, add water up to the level of the LC liquid.

  3. Manual Cycle: Set Manual for 20 minutes and let it run.

  4. Cool and Use: After the cycle, let it cool. Some caramelization may occur, but it won’t harm your culture.

Grain Prep (WBS and Oats)

WBS (Wild Bird Seed):

  1. Heat Water: Fill the Instant Pot 2/3 full with hot water and set it to Steam. Close the lid, vent open.

  2. Add WBS: Slowly add 2 quarts of WBS to prevent boil-over. Close the lid and set to Seal. Hit Cancel and start Warm function.

  3. Steam Off: After 20 minutes, strain WBS and let it steam off.

  4. Jar Loading: Divide WBS into 4 quart jars, screw lids on, and cover with foil.

Oats:

  1. Prepare Oats: Add 1.75 quarts of oats to the pot and fill with hot water 3/4 full.

  2. Steam Cycle: Set the Steam function for 30 minutes with the valve on Vent.

  3. Dry Grains: After the cycle, strain the oats and let them steam off, preferably overnight.

  4. Jar Loading: Divide oats into 4 jars, screw lids on, and cover with foil.

Sterilization: Spawn Jars

  1. Load Jars: Place prepared spawn jars in the Instant Pot without the rack. Fill with hot water up to 1/3 of the jars.

  2. Manual Cycle: Set the Manual cycle for 3 hours at high pressure. Instant Pots don't reach 15 psi but can reach 242°F, so run the cycle longer.

  3. Vent and Walk Away: Vent steam for 5 minutes after it reaches pressure, then seal the vent.

Tools Sterilization

  1. Prepare Tools: Wrap scalpels, tweezers, etc., in foil and place them in a glass jar.

  2. Set Up Pot: Place the jar in the Instant Pot on the rack. Add hot water to the level of the rack.

  3. Manual Cycle: Set Manual for 15 minutes. Vent steam for 5 minutes before sealing.

Sous Vide Function

If your Instant Pot has a sous vide function, you can set it to 120°F to keep sterilized agar or LC at the perfect pourable temperature without overheating. You can also use it to melt stored agar by setting it to 185-190°F, then cooling to 120°F for pouring.