Calculate which one of the below results in better sterilization. Assume saturated steam in both cases. Show calculations and explain the rationale.
SIP of bioreactor done at 124 deg C for 15 min, takes about 20 min to heat up, and 60 min to cool down.
2. SIP of bioreactor done at 111 deg C for 60 min, takes about 12 min to heat up and 35 min to cool down
What does “better sterilization” mean to you?
In terms of sterility assurance, and assuming this is moist heat sterilization, the process lethality (F0) can be used as a measurment of process effectiveness. More lethality gives better sterility assurance (SAL).
The first option: 124°C for 15 min, has more lethality (F0 = 29.2 min), than the second option (F0 = 5.9 min); so for sterility assurance, the first option can be considered “better sterilization” in terms of process lethality.