Potatoes are often differentiated according to age. They may be sold soon after they are dug, or kept in cold storage for up to a year before sale.
Only potatoes that are freshly harvested before maturity are correctly designated as “new.” Many consumers believe that “new” simply denotes a small, round red or white potato. But true new potatoes have thin “feathering” skins that can be brushed off with your fingers. Mature potatoes, by contrast, have thick skins. Supermarkets often offer "new " or "baby" potatoes, which for the most part are not really very new.
New potatoes may be as small as marbles or as large as full-sized mature potatoes. Most are harvested when they are about the size of a golf ball. Genuine new potatoes have a high moisture and sugar content, so they cook quickly and have a delicate, sweet flavor.
In the supermarket, potatoes are sometimes labeled according to their end use: baking potatoes, all-purpose potatoes, or boiling potatoes.
Baking potatoes have a low-moisture, high-starch content, with a so-called “mealy” flesh. This makes them fluffier than other potatoes when baked or mashed. They are not suited to cutting into chunks for salad, because they will fall apart when cooked.
Boiling potatoes have high moisture and low starch and what is called “waxy flesh.” These potatoes do not do well when mashed; they get gluey. Boiling potatoes are best for potato salads because they hold their shape well when cut into chunks.
All-purpose potatoes can be used either as baking potatoes or boiling potatoes, since their starch and sugar contents are between those of the mealy-fleshed and the waxy-fleshed potatoes.
Potatoes come in dozens of shapes and skin colors, from yellow and tan to orange and red to blue and purple. Some varieties with colored skin have white or yellow flesh inside. Others have flesh whose color more or less matches their skin’s. Here are some of the types of potatoes you can find in stores or in farmers’ markets.
- Fingerling potato: With thin, tender skins and small size, fingerling potatoes are not new potatoes. Rather, they are cultivars of potatoes—often of heritage varieties—bred to naturally grow to only a small size and narrow width. Unlike new potatoes, fingerlings are harvested at maturity, which means that they have time to develop more complexity of flavor—sometimes described as “nutty”—and that they store well. You can find them in a variety of colors, including yellow, orange, red, blue/purple, and of course white. Popular varieties include the Russian Banana, French (orange skin), Butterfinger, Purple Peruvian, Red Thumb and the LaRatte.
- Finnish yellow wax potato: This waxy potato has deep yellow flesh. Its rich taste and “buttery” appearance may convince you to forgo butter.
- Long russet potato: Typified by the Russet Burbank, these are the favorites among baking potatoes and are the leading variety grown. Most “Idaho” baking potatoes are Russet Burbanks. These large, oval-shaped potatoes, which can weigh up to 18 ounces each, have a hard brown skin and starchy flesh. Typical of a russet is a fine netting pattern over the skin called “russeting.”
- Long white potato: The White Rose is one of the better-known varieties of all-purpose potatoes. When new, they are thin-skinned and waxy; when mature, they are starchy and weigh an average of half a pound.
- Marble potato: These are tiny (yes, marble-sized) potatoes. They are very small versions of one or another of the round red or round white potato varieties.
- Round red potato: These red, smooth-skinned boiling potatoes, notably the Red LaSoda and Red Pontiac, are most commonly sold “new” or small. But they are also available in larger sizes.
- Round white potato: The Katahdin (the principal variety grown in Maine) and the Kennebec are representative of these multipurpose potatoes. They have a light tan skin and are smaller than the long whites, averaging three per pound.
- Yukon gold potato: These are yellow-fleshed all-purpose potatoes, fine for baking or boiling.
Click here to learn how to store potatoes safely.