Have you ever stood in front of a colorful array of root vegetables, wondering what the heck the difference is between a sweet potato and a yam? Does it matter? With Thanksgiving upon us, you’ll want to be prepared to amaze your guests with horticultural trivia and sweet potato history, so let’s get this straight.
Furthermore, if sweet potatoes are so sweet, what’s with the traditional marshmallow-adorned, brown-sugar-sweetened casserole that graces so many holiday tables? Are sweet potatoes so lacking in sugar that more is needed to make them sweet?
The sweet potato is sweet, indeed. Every 3.5-ounce serving yields about 4.2 grams of sugar, but don’t let that scare you. The sweet potato, rich in fiber, vitamins and minerals, should by no means be avoided. It’s higher than carrots in vitamin A and packs a good amount of calcium, too – about 30 mg per serving.
The earliest known cultivation of sweet potatoes was in Peru, at about 750 BC, but food historians suspect they were grown and eaten even a couple of thousand years before that. By the 15th century, they were growing throughout Central and South America, and Columbus “discovered” them growing in the West Indies, promptly sending them back to Spain. Now, sweet potatoes grow throughout the world in all warm, moist climates. Yams, on the other hand, are native to Africa and are starchier and drier; they’re part of the lily family and not even closely related to the sweet potato.
A 16th-century English herbalist, John Gerard, praised the sweet potato for “procuring bodily lust,” in addition to its nourishing qualities. Could this be why King Henry VIII was said to consume massive amounts of sweet potatoes, usually in the form of sweet potato pie? Or, did he just think them delicious?
The sweet potato is botanically related to the morning glory, and hundreds of varieties are cultivated in the United States in colors ranging from light yellow to deep orange. But you’ll find just a handful of those varieties in New Hampshire. Sweet potatoes prefer a long, warm, moist growing season, so growing them in New Hampshire takes special care and attention to keep soil warm and extend the season. Further from home, southern states like North Carolina and Louisiana lead the United States in sweet potato production, followed by California.
Confusion between sweet potatoes and yams set in way back in history, when slaves working the fields in the southern colonies called sweet potatoes yams because they looked like the edible wild tubers of their homeland. To complicate matters, even today, the USDA requires labels including the term “yam” to also include the term “sweet potato”–an intended clarification that has only perpetuated confusion. Some sweet potato varieties add to the nonsense with confusing names like that of the beautiful “garnet yam,” a sweet potato, in spite of its name. Adding yet another layer of craziness, Europeans will often refer to sweet potatoes as simply potatoes.
Confused yet? Since you’re unlikely to find true yams anywhere other than in an international market, you can be comfortable that you’re probably buying sweet potatoes. The easiest way of all to be sure is to buy sweet potatoes grown locally, from one of the many area farms that grow them these days, and ask the farmer if you’re still not sure!
At the market or the farm stand, look for firm, relatively undamaged skin with no white areas or soft spots. Size does not matter; large and small sweet potatoes are equally sweet. They bruise easily, so treat them gently. It’s best to buy organic sweet potatoes, not only because you might be eating the skin, but because the non-organic ones can absorb a musty flavor if exposed to pesticides. Store them like potatoes, in a cool, dry, well-ventilated, dark place. About 55 degrees is optimum. Storing them in the refrigerator will cause a tough core and off flavor to develop. A sweet potato stored on the counter will stay fresh only for about one week; a cooler spot will keep them fresh for a few weeks.
Although sweet potatoes can be eaten raw, cooking converts the starches to that sweet, sweet goodness we appreciate so much. As with most vegetables, simply steaming sweet potatoes will yield the most nutritious result. (Just steam ½ inch slices for 6 to 8 minutes.) For variety, though, they’re easy to stir fry, roast or mash. Once mashed, they can transform into casseroles, sweet deserts and sweet potato rolls. They don’t need added sugar to be sweet, but a little bit will bring out their natural sweetness. Sweet potatoes pair well with spices like cinnamon, allspice and ginger, but try preparing them with garden herbs like thyme, rosemary and sage, too.
Try roasting cubed sweet potatoes, sliced apples and crumbled sage, tossed with a little maple syrup and melted butter, for an aromatic, marshmallow-free side dish.
Here’s a super simple, old-fashioned recipe for glazed sweet potatoes. It comes to us from Sweet Potato Culture for Profit, by R.H. Price, published in 1896.
“Select potatoes of uniform size, pare and trim them into long oval shape. Cook in boiling salted water until nearly tender. Mix quarter of a cup of sugar and the same of butter and melt them in half a cup of hot water. Arrange the potatoes in a granite pan. Moisten them with the sugar mixture. Set them in the oven and baste frequently with this syrup. Cook until they are covered with a rich brown glaze, but be careful not to let them burn.”
So, it’s possible to leave the marshmallows at the grocery store for next summer’s camping trip. At my Thanksgiving table, this dish will feature New Hampshire maple syrup, rather than sugar, and I’ll therefore skip the water in the glaze. And I’ll steam the sweet potatoes to make sure we’re getting every bit of the nutrients they have to offer. No fussing with fancy recipes for this cook!
By the way, I don’t have a granite pan – do you?
Eleanor Baron lives, gardens, cooks and writes in Concord and stalks area farmers markets for fresh, in-season produce. Visit her blog at nourishingwords.net for more ideas and inspiration on incorporating healthy habits into your life.