Although potatoes can be stored in a root cellar, canning them can help people make soups or mashed potatoes quickly. Any variety of potato can be used in home canning, but it is best to use only one variety per batch. It is helpful if all the potatoes are the same size, so it can be a good idea to slice them into 1 to 2 inch (2.54 to 5.08 cm) chunks. When canning potatoes, the spuds should be washed carefully and then peeled, as canning them with the peel on could increase the risk of botulism.
Canning potatoes is best immediately after they have been harvested, as this will result in a fresher-tasting product. Even so, home canning may be postponed for a short time if necessary. Store-bought potatoes can also be used when bottling food in this manner. If old potatoes are used in home canning, it is very important to inspect them carefully for signs of rot or insects, and then remove any damaged spots before preparing them.
When canning potatoes, spuds that are slightly soft around the edges yet firm in the center are usually preferred. This requires the potatoes to be boiled for around 10 minutes in order to soften them a little bit. If potatoes are cooked longer than this, they might become mushy when they are processed inside the canning jar.
After the potatoes have been pre-cooked, they are ready to be placed in canning jars. They should be placed in the jars to just below the mouth of the container. Jars should be filled loosely, but not packed too tightly. Once this is done, boiling water should be added over top of the canned potatoes. In order to save time, cooks can boil a separate pot of water on the stove at the same time they are boiling the potatoes.
Canning potatoes is usually performed using a pressure cooker rather than open kettle canning because doing so helps ensure food safety. The jars should be allowed to process at around 10 pounds (4.54 kg) of pressure for around 40 to 45 minutes and then allowed to cool before removing them from the canner. This should be done with special tongs, which are called jar lifters; it is also a good idea for cooks to wear oven mitts and long sleeves in order to keep from being burned by steam from the pressure cooker.