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November, 2010

Sweet Potatoes or Yams

By Dennis Linden

While there are many varieties of sweet potatoes, the agricultural industry has organized them into two categories based upon appearance and texture after being cooked, namely firm or soft.

The pale-skinned sweet potato has a thin, light yellow skin and matching interior that is crumbly firm in texture and fairly neutral in flavor, similar to that of a white baking potato. The darker-skinned variety, which is most often called a yam in error, has a thick, dark orange to reddish skin protecting a vivid orange interior that is sweet and creamy soft in texture when cooked.

The term “yam” as it is generally used in this country is really a bit of verbal piracy for marketing purposes. The word was coined to merchandise the orange sweet potato separately from its pale yellow first-cousin. In the United States, firm varieties (yellow sweet potatoes) were being cultivated long before soft varieties were developed. So, when soft varieties were first grown commercially, there was a need to differentiate between the two. Sweet potatoes are an indigenous crop to the Americas with a history dating back to 750 B.C. in Peruvian records. However, the yam rumor and label got its start by African slaves in the southern states because the sweet potato vaguely resembled the “nyami” of their homeland. A nyami is a huge, black-skinned, starchy, edible tuber that can grow to four feet in length. The word was eventually shortened to "yam” and picked up by the produce industry, which propagated the fictitious distinction between the two.
Botanically speaking, both colors and all varieties offered in the U.S. marketplace today are very much sweet potatoes and only distantly related to the real African yam at all. In fact, today the U.S. Department of Agriculture requires labels with the term “yam” on them to also be accompanied by the term “sweet potato”. Old habits are hard to shake, however, so the American consumer will probably always refer to the orange sweet potato as a yam. Still, it would be wise not to ask for a yam in a grocery store that specializes in African, South American or Caribbean foods without having an extra large grocery cart available to carry it!
Organic sweet potatoes are packed with vitamin A, a nutrient considered critical in maintaining proper eye health. One sweet potato contains nearly eight times an adult’s daily need of this important vitamin, and, because vitamin A is fat-soluble rather than water-soluble, the body can store it for later use. They are also loaded with potassium, which helps maintain electrolyte balance in the body cells, as well as normal heart function and blood pressure.
Sweet Potato

In spite of the name, for diabetics the sugars in a sweet potato are digested easier and slower than a regular potato. The tuber is also relatively low in calories and contains no fat. In fact, since sweet potatoes are healthy and tasty without needing flavor enhancements like butter, sour cream or sugar, their lower caloric count will make them much more appealing than a russet potato slathered with all the fatty extras!

One storage tip: From its rough exterior, one would think it a fairly durable produce item, but it is actually quite temperature sensitive. Keeping sweet potatoes in the refrigerator will cause a hard core and an "off" taste. Store at 50°F to 60°F in paper bag to insure that no moisture can accumulate that will cause tubers to go bad. Below this temperature the starches will convert to sugars, which will trigger the decaying process. Stored at room temperature, sweet potatoes will last about a week; stored slightly lower in the suggested ranges extends that to about one month.

Sweet potatoes can be roasted, sautéed, steam, baked or even chipped. However, when possible cook them whole first as most of the nutrients are next to the skin and skins are easier to remove after they have been cooked. The yellow varieties take longer to cook than the orange. Take advantage of new crop promotions at retail that always occur during these next few months of the holiday season. Then continue to incorporate this wonderfully tasty and nutritious tuber into your year-round diet with the aid of the preparation ideas offered in the this month’s Cooking with the Kids feature on this site that are just as good for adults as they are for kids!