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Sweet potatoes

Why Eat It
Varieties
Availability
Shopping
Storage
Preparation
Nutrition Chart


Why Eat It

Many people eat sweet potatoes only on Thanksgiving, and that's a shame, since they're among the most nutritious of vegetables. Their bright color is a key to their high beta-carotene content, and they also contain the carotenoids lutein and zeaxanthin. Eaten with the skin, a baked sweet potato is an excellent fiber source (about half of which is soluble). And these naturally sweet treats supply substantial amounts of vitamins C and B6, and manganese, as well as a small amount of potassium.

Varieties

There are two basic types of sweet potato: Moist (orange-fleshed) and dry (yellow-fleshed). The sweeter orange-fleshed sweet potato varieties dominate the U.S. market, but some people prefer the starchier yellow-fleshed types. The moist-fleshed potatoes are often called "yams," but this is a misnomer: The true yam (botanical family Dioscoreaceae) is a large (up to 100 pounds) root vegetable grown in Africa and Asia and rarely seen in the western world. However, common usage has made the term "yams" acceptable when referring to sweet potatoes.

Availability

Sweet potatoes---which are grown mainly in California, Louisiana, and New Jersey--are sold throughout the year, but are most abundant in the fall and early winter. Many stores feature sweet potatoes around Thanksgiving and Christmas time.

Sweet potatoes are also sold canned or frozen. The canned potatoes are usually packed in heavy syrup--"candied"--although some processors also pack them in water. Canned sweet potatoes are substantially lower in beta-carotene, vitamin C, and B vitamins than fresh ones.

Shopping

Unless your produce market labels sweet potatoes as being orange- or yellow-fleshed, you may not be sure exactly what you're getting. Although the orange-fleshed type tends to be plumper and its skin a little redder (a hint of the orange flesh below), and the yellow-fleshed type a little narrower with a tan skin, when they aren't side by side, it's pretty difficult to judge the difference. In most instances, you can assume you're getting orange-fleshed sweet potatoes. If you are actively seeking the yellow-fleshed, you should ask the produce manager.

Select sweet potatoes that are heavy for their size, and buy similar-sized potatoes if you plan to cook them whole, so that the cooking time will be uniform. Choose potatoes that are smooth, hard, and free of bruises or decay, which may appear as shriveled or sunken areas or black spots. Even if cut away, a decayed spot may have already imparted an unpleasant flavor to the entire potato.

Storage

Despite their rugged appearance, sweet potatoes have a thin skin that is easily damaged, and they are subject to rapid spoilage. To help preserve them, growers cure them--that is, they store them at a high temperature and humidity for about 10 days before sending them to market. This process also enhances the vegetable's natural sweetness. After purchase, sweet potatoes should be kept in a cool (55°F to 60°F), dry place, such as a cellar, pantry, or garage--never in the refrigerator, where they may develop a hard core and an "off" taste. In fact, when sweet potatoes are stored at low temperatures, their natural sugars turn to starch, which does nothing to enhance their flavor.

Sweet potatoes will keep for a month or longer if stored at 55°F; if kept at normal room temperature, they should be used within a week of purchase.

Sweet potatoes may be somewhat dirty, especially if bought at a farmstand or a farmers' market. You should brush off any excess dirt before storing, but don't wash the potatoes until you are ready to cook them, as the moisture will hasten spoilage.

Cooked sliced or mashed sweet potatoes can be frozen; add a little lemon juice to keep them from darkening and pack them into freezer containers.

Preparation

Moist- and dry-fleshed sweet potatoes are interchangeable in most recipes (except in baked goods, where the difference in the moisture content might be critical).

Scrub the potatoes under cold running water before cooking.

Baking: Pierce the potatoes with a fork before baking to let the steam escape from them. To speed clean-up, place the potatoes on a foil-lined baking sheet to catch the sticky juices that ooze from them as they bake. Cooking time: 30 to 60 minutes in a 400°F oven, depending on size.

Boiling: If you cook the potatoes whole, there's no need to peel them first; the thin skins will slip off easily when the potatoes are done, leaving most of the nutrients intact. The skin is edible, however, and supplies additional dietary fiber. Cooking times: for whole potatoes, 15 to 35 minutes; for chunks, 10 to 15 minutes.

Microwaving: Wash the potatoes and pierce them several times with a fork, then place it on a paper towel. When you take the potatoes out of the oven, wrap in foil and let stand for five to 10 minutes. Cooking times: for two medium potatoes, five to nine minutes; for four, 10 to 13 minutes.

Nutrition Chart

Sweet Potato/1 medium baked

117
Total fat (g)
0.1
Saturated fat (g)
0
Monounsaturated fat (g)
0
Polyunsaturated fat (g)
0.1
Dietary fiber (g)
3.4
2
Carbohydrate (g)
28
Cholesterol (mg)
0
Sodium (mg)
11
Beta-carotene (mg)
15
Vitamin C (mg)
28
Vitamin B6 (mg)
0.3
Manganese (mg)
0.6


Date Published: 04/21/2005
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