News

How Is the Relationship Between Steam Generation and Substrate Quantity Calculated During Sterilization?

In large-scale mushroom cultivation, high-pressure sterilization is typically not used due to the production scale. Instead, ambient temperature and atmospheric pressure sterilization methods are adopted to meet production needs while reducing costs. Once the raw materials for mushroom cultivation are processed into bagged substrates, they must be sterilized and disinfected immediately and thoroughly. The sterilization process directly affects the quality of the substrate and the risk of contamination by foreign microorganisms. To prevent contamination or acidification of the bagged substrate, the time from mixing and bagging to sterilization should not exceed six hours. Atmospheric pressure sterilization is recommended instead of using pressure cookers.

Key Points for Atmospheric Pressure Sterilization

1. Temperature and Duration Requirements

• The temperature should rise quickly to 100°C.

• Begin timing when the temperature reaches 100°C.

• Maintain this temperature for 10–12 hours to ensure thorough sterilization.

Some mushroom growers often neglect this step, leading to incomplete sterilization and contamination by foreign microorganisms. This affects mycelium growth and reduces yields. Certain highly resistant contaminants require continuous exposure to 100°C for 12 hours for complete eradication.

2. Sterilization Data Focus

• Sterilization effectiveness depends on temperature and time, not the quantity of steam generated or the amount of substrate.

• Start timing only when the substrate temperature reaches 100°C and sustain it for 12 hours to achieve complete sterilization.

Process and Tips for Effective Sterilization

• Water Management
  Ensure sufficient water in the sterilization chamber. Add hot or warm water hourly as needed to maintain consistent temperature. Avoid adding cold water, which may reduce the temperature and compromise the sterilization process.

• Proper Bag Arrangement
  Arrange the bags in the sterilization chamber to allow adequate airflow and ensure even heat distribution. Prevent dead spots that could lead to incomplete sterilization.

• Fire Control
  Use a heating strategy:

  Avoid the "big start, weak finish, loose middle" scenario, which can result in incomplete sterilization, wasted materials, and economic losses.

• Use high heat initially to raise the substrate temperature to 100°C within four hours.

• Maintain the temperature for approximately 10 hours with controlled heating.

• Apply high heat for at least one hour during the final phase.

• “Attack at the Start, Maintain in the Middle, Secure at the End”

• Prevent Steam Leakage
  Use cotton, cloth, or plastic film to seal any leaks in the sterilization chamber effectively.

• Post-Sterilization
  Wait 24 hours after sterilization before removing the bags from the chamber.

Importance of Thorough Sterilization

Sterilization is the most critical step in the entire mushroom cultivation process. It directly impacts the sterilization level, substrate quality, yield, and overall economic efficiency.