Potatoes appear at the table in so many different, delicious guises: mashed, baked, sautéed, boiled. And as a cook, you probably know that for each of these dishes, some kinds of potatoes work better than others: russets are great for mashing and baking; round whites for sautéing; little red potatoes for boiling whole. But why is this so?
To answer that question, let’s take a closer look at what happens to a potato—any potato—during cooking. Unlike most vegetables, which lose water during cooking as their cell walls soften and release moisture, potatoes actually absorb water. Raw potatoes contain lots of microscopic starch granules, and as the starches soften in the heat of cooking, they sponge up surrounding moisture. The amount of moisture absorbed influences the cooked potato’s texture and shape. Thus, starch content is a key to determining a potato’s best use.
A matching game: varieties and uses
At the supermarket, you’ll find potatoes in all sorts of shapes, colors, and sizes. In addition to these obvious differences, potatoes also vary in starch content. In recipes, high-starch potatoes are sometimes referred to as “mealy” potatoes, and low-starch potatoes are often termed “waxy.” It would be a great help to cooks if supermarkets labeled potatoes as high-, medium-, or low-starch varieties. Unfortunately, not many stores do, so here’s the lowdown.
High-starch potatoes are for baking and mashing
Potatoes such as russets, Idahoes, and Russet Burbanks are high in starch and lower in moisture. They have thick skins, so they bake to perfection and make the fluffiest mashed potatoes. As they cook, their cells tend to separate and absorb lots of moisture, which creates their characteristic mealy, fluffy texture. When you eat these potatoes, you can sense their abundance of starch, as they feel granular and dry on your tongue.
The moisture-absorbing quality of high-starch potatoes also makes them good thickeners in soups. As chunks of highstarch potatoes cook in a soup, the potato falls apart, releasing starch granules into the broth, where they sop up liquid and thicken the soup. But that same quality prevents these potatoes from holding together during cooking, so they’re not ideal for any dish where you want the potato to hold its shape: scalloped potatoes, whole roasted, or hash browns.
High starch: the secret to perfect french fries. High-starch potatoes are your best bet for frying. Picture a freshly cut fry as it hits hot fat. Starch granules on the outside immediately swell in the heat and start pulling moisture from the interior of the potato. As the outside cooks and browns, the surface seals, preventing the french fry from absorbing lots of cooking fat. And what you get is a french fry with a crisp and golden exterior and a dry, fluffy interior.
Medium-starch potatoes are mult-purpose
Yukon Golds, with their slightly nutty flavor, and Yellow Finns, with their golden skin and flesh, have less starch and a creamier texture than high-starch potatoes. You can mash medium-starch potatoes if you like (and a lot of people do), but expect the result to be creamy rather than light and fluffy. Some cooks also prefer the in-between starch content of these potatoes for pan-fried potatoes and potato salads.
Q: Why shouldn’t I refrigerate raw potatoes?
A: Potatoes should be stored in a dark, cool (45° to 50°F), dry place. If the temperature is too cold, some of the potatoes’ starches will turn into sugars. Not only does this taste unpleasant, but the extra sugars also lead to overbrowning during cooking. If a potato winds up in cold storage, you can convert the sugars back to starches by storing it at room temperature for a few days.
Low-starch potatoes are for salads, gratins, and roasting
Red-skinned potatoes and round whites, are considered “waxy.” When you slice into one of these high-moisture, low-starch potatoes, the flesh looks translucent and firm.
The cells of low-starch potatoes adhere to one another and swell little during cooking, so these potatoes hold their shape and don’t fall apart easily when handled. And they contain more sugar, which turns deliciously brown during cooking. These qualities make them suited equally well for boiling, roasting, or sautéing. The flesh contains less starch and more sugar so it remains moist and toothsome even while the outside becomes
crisp and brown.
We love little waxy potatoes boiled and served whole with butter and parsley. Waxy potatoes are also ideal for scalloped potatoes because their slices retain a pretty shape and appealing texture during cooking, instead of disintegrating into the surrounding sauce. Because of their low starch content, these varieties only lightly absorb salad dressing, so use them if you like a potato salad that’s chunky, rather than creamy.