121 ℃ is the "gold standard" for fermentation sterilization that has been verified through long-term practice

This temperature is not set arbitrarily - it can kill the most difficult "nail households", such as bacterial spores (dormant bodies like Bacillus subtilis that cannot be boiled), mold spores, and even bacteriophages cannot withstand it.

It can be said that 121 ℃ is the "gold standard" that has been verified through long-term practice.

If the factory used to frequently get infected with bacteria or produce high value-added products (such as antibiotics and amino acids), some companies may slightly raise the temperature, such as to 128 ℃ or even 130 ℃, and the time may be extended to 30-45 minutes, mainly for safety reasons, especially when sterilizing empty cans (without culture medium).

However, it should be noted that higher is not necessarily better.  

If the tank has already been filled with culture medium, especially those containing sugar, protein, or vitamins, and the temperature is too high or the time is too long, the nutrients are easily "burnt" or decomposed, which in turn affects the subsequent fermentation effect.

So we need to find a balance between "thorough sterilization" and "protecting nutrition".

In addition, just looking at the temperature is not enough - the steam needs to be saturated, the condensed water needs to be drained completely, and the dead corners inside the tank need to be blown through, otherwise the local temperature is not enough, and bacteria can still be infected.

Just a brief note:

✅  Daily sterilization: 121 ℃, 20-30 minutes

✅  High risk situation: Consider 128-130 ℃

✅  The key is: sufficient steam, enough time, and standardized operation

This is both safe and practical, without making it too complicated.