I have an Instant Pot Max with a canning feature. Setting up the pot requires entering your altitude. One app that I used says I live at 921 feet, but my landlady says I live at 928 feet. My question is: Which do I use?
Canning with pressure cookers and canners
I know that the Instant Pot Max has a button for canning, however, the research done by the National Center for Home Food Preservation found that it is not safe for canning because the temperature fluctuates during processing. This fluctuation can cause under-processing and you can risk foodborne illness.
The following publication will give you specific information on the safety of Electric Multicookers:
- Safely Canning Foods: Pressure Canners, Pressure Cookers and Electric Pressure Cookers, OSU Extension
That said, the Presto Digital Electric Pressure Canner was developed specifically for canning, not cooking, and they have followed the USDA protocol and procedures for safe canning. On page 10 of the publication below you can read the information about the Presto canner and multicooker safety:
- Use, Care and Operation of Your Pressure Canner, University of Idaho Extension
Regarding your question about altitude: the pressure and time for processing changes when you are canning at altitudes over 1000 feet. So, if you are under 1000 feet, the exact altitude wouldn't really matter.