What is the difference between a pressure cooker and a pressure canner?
Some will say that pressure cookers and pressure canners are more or less the same thing. And partially they are right!
They both use pressure cooking as their cooking method. Pressure cookers and canners are both airtight and because of that pressure builds up, the trapped steam can’t escape and the internal temperature rises beyond what it would under normal room pressure. As a result of that food cooks much faster.
The main difference between pressure cookers and canners is their size. Even though, pressure canners can be used both for cooking and canning, they have to be large enough to accommodate a certain number of jars on the bottom. Because of that pressure canners are larger in size (their capacity goes from 10 Quart and up) and therefore they are not very practical for pressure cooking. The size of pressure cookers goes from 3.7 to 8 Quart and they are more suitable for everyday use.
Pressure canners are usually made of aluminum, while pressure cookers are made of stainless steel, aluminum or a combination of both (the aluminum is encapsulated between the stainless steel). You can find pressure cookers that combine stainless steel and copper (a little bit more expensive). Aluminum and copper are used to compensate the lower thermal conductivity of stainless steel. On the other hand stainless steel is easy to clean and is very durable.
Pressure canning requires the use of different working pressure values. The pressure you are going to use depends from the size of the jars and the acidity of the food you are canning. So, your pressure canner must have different pressure settings. Usually there are three pressure settings (5, 10 and 15 psi).
Pressure cookers, on the other hand, have one or two pressure settings. Usually the standard pressure for cookers is 15 psi, but many pressure cookers have a second lower pressure setting for cooking certain delicate ingredients. Remember that cooking times increase with the lowering of the pressure. So, if you choose to buy a pressure cooker with 10 or 12 psi of working pressure your cooking times will increase for 20-50%.
When you are pressure canning or cooking take into consideration the altitude of your location as well, because you need to increase the working pressure on higher altitudes.
Pressure cookers have sealing rings or gaskets that form a gas-tight seal between the lid and the pot preventing the steam and the air from escaping (steam can only escape through the built-in regulators on the lid). Gaskets are usually rubber or silicone rings.
Certain pressure canners have special metal-to-metal sealing systems that can be very handy because you don’t have to clean, store and eventually replace the gaskets.