There’s always been some confusion here and what’s worse, there are many people with loud yet unfounded opinions. As an experienced canner and food safety researcher, I have some true insights.
A pressure cooker can be used for home canning. There is no technical difference between a pressure cooker and a pressure canner. Some pressure cookers do not have a finely calibrated and controlled pressure system and are not suitable for controlled pressure canning. Very small pressure cookers are not recommended for canning.
Let’s get into the technical and practical requirements for a safe pressure canner.
Pressure Canners vs Pressure Cookers for Canning
Pressure Acnners are traditionally just a large pressure cooker. Common pressure canners are 21 to 23 quarts (will hold that much liquid), while most units sold as pressure cookers are 8-quart or under. It’s mostly a difference in size. That size can make a difference.
Pressure canners are required to have two things according to the USDA. They need a well-calibrated and simple pressure control system, and they need a way to vent steam after heating, before pressurizing.
Not all pressure canners use a dial gauge to monitor pressure. That’s one common misconception that I hear. I have had numerous well-meaning and long-winded housewives tell me that I can’t pressure can in a unit without a dial gauge. That’s not true according to either the manufacturers or the USDA.
Last week I bought a brand-name pressure canner, the 22-quart Mirro, and it doesn’t have a dial gauge. All traditional pressure canners and pressure cookers use either a jiggler weight or a dial gauge and counterweight system as a pressure control.
What you should avoid is using electric pressure cookers for pressure canning. Some of them, notably the Insta-Pot, have been shown to be poorly calibrated. while it still works fine for cooking, it can be problematic for certain canning operations.
There are some electric pressure canners on the market. That’s different. While they remain untested by the USDA (they’ve hardly done any tests since 1978), manufacturers have tested them thoroughly and you can trust the manufacturer’s recommendations for operation. They’re the real expert.
If you’re lookiong fior a pressure canner, Check out this article: Best Pressure Canners for Beginners
Dangers of Canning in a Small Pressure Cooker
According to the USDA and National Center for Home Food Preservation, using a small pressure cooker can possibly alter the time needed for safe processing. It’s recommended that a unit hold at least four quart jars in the upright position to be used for pressure canning.
The most common sizes of pressure cookers are 16, 21, 22, and 23 quarts. Some smaller units are sold as pressure canners or pressure cookers/canners. The smallest that usually fits four quart jars is an 8-quart or a 10-quart pot, depending on the dimensions of the pot.
The issue, or potential issue, is that the USDA testing was done with larger pots. Large pots have a longer heat-up time. If it takes my 45 minutes to heat a 23-quart to a boil (212 degrees F), then it technically started the pasteurization process 20 minutes earlier, at about 160 degrees F.
A small pot may heat up to a boil, and thus ready for pressuring in 10 minutes. That means it had maybe 5 minutes of pre-pasteurization. When the USDA came up with the recommended processing time tables for pressure canning, they did so using the larger units.
The time under pressure recommended to kill bacteria was developed from the bigger pots so in theory it should be slightly different for the smaller ones. Now, it can get confusing here.
The recommended timeframes have a large safety margin for good measure. But, is that safety margin enough to justify using a small pot? Maybe. The USDA originally made the recommendation that home canners add 10 minutes to the processing time for a small (less than 8-quart) pressure canner.
They since dropped that recommendation and made the statement that ‘there are many sizes of pressure saucepans and they haven’t all been tested’.
I use a 6-quart Presto pressure coker for canning, and reccomend that one to all my friends who may want a small unit. It holds two quart jars or four pints, and it does a fantastic job. Presto makes an 8-quart pressure cooker that holds four quart jars or eight pints. It’s also a great option for a small pressure caner.
The 6 and 8-quart Presto pressure cookers have a reliable pressure controll and stream vent system, and a very durrable gasket seal. I will constantly reccomend them to people who wan ta cheaper, smaller way to pressure can.
If you hae any questions, ask in the comment section below. I’ll reply.
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