Not known for their fragility, potatoes are a robust, starchy tuber in the nightshade family (along with fellow Solanaceae family members tomatoes, eggplants, and peppers). Potatoes pack a nutritional punch, weighing in with substantial amounts of potassium, fiber, protein, vitamin C, Vitamin B-6, Magnesium, and a lesser but still notable amount of Iron.
It’s easy enough to store fresh white potatoes for up to 2 months in a cupboard kept at 50-70°F (sweet potatoes last only 2-3 weeks). But what if you want them to last even longer?
Interestingly, storing white potatoes in a refrigerator is likely to diminish their quality and they are expected to last only 1-2 weeks there. Alternatively, you could cook and mash them, stuff them, or scallop them for freezer storage, but again, they will retain best quality only for a few weeks in the freezer.
Drying is an option for making potatoes last longer. Wash, peel, then cut potatoes into 1/4-inch thick shoestring strips, or cut into 1/8-inch thick slices. Steam blanch the prepared pieces for 6-8 minutes or water blanch them for 5-6 minutes. Plan for a drying time of 8-12 hours in a dehydrator and up to twice as long in an oven, depending on circulation. If you dry sweet potatoes and want to rehydrate them for a recipe, combine each cup of dried pieces with 1-1/2 cups water and let them soak for 30 minutes.
As for canning potatoes, our recommendation is to peel potatoes before canning. That style of preparation is how the research was carried out to determine the recommended processing, and in order to know that the peeling does or does not make a difference, research would need to be done with unpeeled potatoes. Different assumptions might be needed in assessing just how many spores of C. botulinum or other bacteria might be present at the start of the process and what amount of heat might be needed to meet standards for the risk of possible survivors. We do not know of research of canning potatoes with peels left on, so we recommend the preparation steps provided with the process recommendation, especially because there is a possibility that the deviation could result in a less safe situation. Also due to safety concerns, it is important to use potatoes that are only 1 to 2 inches in diameter if you are canning them whole. These are sometimes described as “new” potatoes; the idea is to use less mature, smaller potatoes which tend to be less starchy than older, “grown-up” potatoes.
White potatoes for canning should be the “waxy” or “boiling” kind. Different types of potatoes have different amounts and types of starches and they react to heating differently. You want a potato that keeps its shape and texture well after a lot of heating, and not one that falls apart, becomes “fluffy” after cooking, and is better for mashing. Most red-skin potatoes are of lower starch than baking potatoes and work well for canning. Many white round potatoes with thin skins fall into this category with red-skin potatoes too. Russets are not good for canning but are good for baking (they have a high starch content). Yukon Gold may not be the best potatoes for canning. While they seem good for boiling, they do tend to fall apart when overcooked. From what we have read, there is a wide variety in the types and amounts of starches in blue potatoes, so not all blues are the same, just like not all white potatoes are the same in these characteristics.
Sweet potatoes can be slightly larger, but medium-sized potatoes should be cut to fit in the jar in uniform-sized pieces. Note that the sweet potato pressure canning process time is significantly longer than for white potatoes.
Sweet potatoes can have a sugar syrup for canning, if you like that style. But otherwise, all potatoes — white or sweet — should have fresh, boiling water prepared to pour over the preheated potatoes. Do not use the cooking liquid. That cooking water contains a lot of starch that comes out of the potatoes and the process time was determined using fresh boiling water to cover. The added starch can create a safety problem by slowing down heating of the potatoes in the canner, and it also creates a very unappealing pack with possible masses of gelled or congealed starches around the potatoes. If you have spoilage, this makes it very hard to see the signs of some spoilage.
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