Sterilization temperature and pressure of steamer

Sterilization using a retort, or high-temperature cooking, is a process where food is subjected to elevated temperatures under pressure to eliminate bacteria and spores, thereby extending shelf life. Common sterilization conditions include 121°C for 30 minutes or 135°C for 15 minutes, requiring a pressurized stainless steel container and steam boiler.

The pressure gauge on the retort typically reads 0.18–0.2 MPa during sterilization. However, this gauge pressure is relative to atmospheric pressure. Absolute pressure, measured from a vacuum, includes atmospheric pressure, which varies by location and altitude. For instance, standard atmospheric pressure at sea level is 0.101 MPa, and gauge pressure is calculated as absolute pressure minus atmospheric pressure.

To determine the correct gauge pressure for sterilization, atmospheric pressure at the production site must be considered. For example, in cities like Yingkou, Guiyang, Changsha, and Chengdu, winter atmospheric pressures range from 0.089 to 0.102 MPa. Adjustments to gauge pressure are necessary based on altitude and seasonal variations to achieve the desired sterilization temperature.