IPOMOEA BATATAS
THEROOT we know as the sweet potato is, in fact, not related to the common white potato at all, but is a tuberous form of morning glory of the genus Ipomoea. It’s easy enough to see the relationship when you see the plant’s vines climbing up a trellis and opening small, rosy-pink, morning glory–like flowers.
As far as names go, sweet potatoes are actually the original “potato.” When Columbus reached the New World, the Native Americans he encountered showed him the sweet potato and called it batata, hence its species name. When Spanish adventurers later discovered the white potato, it bore a resemblance to batata, or patata as they sometimes called it, and the name was transferred by the Spanish to white potatoes.
The word “sweet” was bestowed by the English as a way to tell it apart from white potatoes. It was a sweet potato, with the emphasis on potato. But since the English language has a tendency to move emphasis to the front, over time emphasis shifted to the word sweet, and eventually people started thinking of sweet potatoes as distinct food.
Although the Spanish brought sweet potatoes to the Philippines in the mid-1500s (and thence to China and the rest of Asia), they had already been grown on the Polynesian islands of the South Pacific and as far west as New Zealand for hundreds of years. This was one of the clues that led Thor Heyerdahl to posit that people from the Americas sailed in reed rafts across the Pacific. Another clue was that the ancient Peruvian word for sweet potato, kumar, was found in languages of the Pacific islanders as kumala, gumala, and umala.
A more contemporary naming confusion relates to the difference between a sweet potato and a yam—many Americans think they are the same thing. In fact, the sweet potato bears no relation to any of the yam species (of the genus Dioscorea) grown in Africa and Asia. Our tendency to use the word yams to refer to extra sweet, yellow- or orange-fleshed forms of the sweet potato is an artifact of the slave trade, when slaves being transported to the New World were fed true yams during their trans-Atlantic voyage, and the name was then transferred to the tropical New World native ipomoea.
THE ORGANIC FACTOR
Scientists are hurriedly trying to develop disease resistance in and otherwise “improve” the sweet potato through genetic engineering. A project at Fort Valley State College in Georgia looks to add foreign genes to sweet potatoes, supposedly to create plants with “superior horticultural traits.” All the more reason to locate and eat organic sweet potatoes. The scientists at Fort Valley don’t say what “foreign genes” will be inserted into sweet potatoes, nor do we know how the additions can affect sweet potato agriculture or the potato consumers. I for one like sweet potatoes just the way they are, without having to wonder whether they contain frog or chicken genes.
NUTRITION
Sweet potatoes have a nutritional edge over regular potatoes due to their rich stores of beta-carotene, which colors their flesh yellow and orange and converts in our bodies into vitamin A. This conversion is stimulated when fats are ingested, which makes it wise to have a bit of butter with your sweet potatoes. They contain about 16 percent starch and 6 percent sugar, but the level of enzymes that convert starch to sugar increases when they are held in storage after harvest. That’s why, although they are a tropical native and grow over a long, warm summer, the season for the best roots is from November to March. That’s when conversion of starch to sugar is maximized and flavor is best. They also contain good amounts of dietary fiber, vitamin B6, magnesium, and 23 milligrams of vitamin C per 100 grams (about three ounces) of sweet potato.
TYPES
Depending on the variety, sweet potato skins can be white, yellow, red, tan, brown, or purplish red. The flesh varies from white to orange.
Having said that, as a rule of thumb, sweet potatoes can be divided into two main types. The first type has orange flesh and is moist, creamy, and squash-like when cooked. These are the sweet potatoes that came from North and South America as well as Australia. ....read more
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