Sweet Potatoes vs Yams

I Yam What I Yam!

You know, you would think “Iron Chefs” would really be on top of things when it comes to food, especially proper culinary terminology. Alas, such is not always the case. Take, for instance, “Iron Chef” Michael Symon. I swear, if I hear him refer to the browning of meat as “caramelizing” one more time, I'm going to throw something at the TV. Meat browns through the Maillard reaction. It does not “caramelize.” It's like he's afraid “browning” doesn't sound “cheffy” enough, so he uses the “fancy word” instead. And he's wrong. If you put a glaze of some sort on a piece of meat, something that contains sugars, and then throw that glazed meat in a pan, the sugars in the glaze will “caramelize.” Otherwise, the meat itself simply “browns.”

And I recently heard “Iron Chef” Marc Forgione, when referring to a standard Thanksgiving dish, utter the phrase, “candied yams, also known as sweet potatoes.” I can only guess he must have been absent the day they discussed yams and sweet potatoes at culinary school. Ooops, that's right......he didn't go to culinary school. But with a Michelin star to his credit, you'd think he'd know the difference, right? And there is a big difference. Here's the skinny.

The Covington Sweet Potato
(North Carolina Sweet Potato Commission)

The so-called “sweet potato,” or Ipomoea batatas” for you Latin-loving scientific types, is a member of the Morning Glory family. It's a dicotyledon, meaning its seeds have two embryonic leaves. Although widely grown in the United States, with North Carolina and Louisiana leading the sweet potato producing pack, the plant originated in the tropical regions of the Americas, around Peru and Ecuador, before migrating north, where it was being grown by natives on the Eastern coastal plain of North America when Columbus came to town.

African Yam

Yams, on the other hand, were imported to the New World from West Africa. Scientifically, they are of the Dioscorea species and occupy a plant family all their own. A yam is a monocotyledon, having only one embryonic leaf, making it more closely related to a grass than to a broad-leaf plant. And they still don't hail from these parts; their tropical growth requirements mean that the rare yams you encounter in your neighborhood specialty market probably came from somewhere in the Caribbean.

One has only to look at the two side by side to see the difference. Sweet potatoes are smooth skinned and are kind of short and round with tapered ends. They look very much like really big potatoes. Yams are downright ugly by comparison, being long and cylindrical with rough, scaly skins and funky little protuberances or “toes” all over them. And yams can grow up to eight feet in length and weigh in at a hundred pounds. Sweet potatoes weigh about a pound and top out around a foot in length. You'll know the difference in your mouth, as well. Sweet potatoes are.....well......sweet, and very moist, too. Yams are dry and starchy.

There's also a significant nutritional difference. Sweet potatoes are rich in numerous vitamins, minerals, fiber, complex carbohydrates, and of course, the beta carotene that gives them their distinct coloring. Yams are a good source of starch and not much else.


The O'Henry Sweet Potato
(North Carolina Sweet Potato Commission)

So why all the confusion between the two? It's pretty obvious they're nothing alike, right? Some people trace the muddle back to the days when African slaves worked the fields and called the root vegetable they encountered by the name they applied to the tuber with which they were most familiar; “nyami,” a word quickly Anglicized to “yam.” But it took the government to really screw things up. See, the “original” sweet potato, the one traditionally grown on the East coast, is white or whitish-yellow in color. You sometimes see them in stores labeled as “white sweet potatoes.” The orange variety now commonly associated with the name didn't actually come to prominence until some Louisiana growers popularized them in the mid-20^th century. A bad cotton crop in the 1930s turned a lot of Louisiana farmers into sweet potato producers. They wanted their product to be clearly distinguished from the plain old East coast variety, so they started calling them “yams” and petitioned the USDA to sanction that label, which it promptly did. Although, if you look at the fine print on the can, you'll find that “yams” labeled as such still have to contain the words “sweet potato” somewhere in the description. But, thanks in part to successful marketing, the orange variety soon overtook the culinary world and the terms “yam” and “sweet potato” became interchangeable in cookbooks and recipes. Nowadays, the traditional “white” sweet potato is looked upon as the odd duck in the flock – unless you're in sweet potato loving North Carolina, where it's just one among the pantheon of varieties designated as the official state vegetable of The Old North State. (The varieties include Beauregard, Covington, Carolina Rose, Carolina Ruby, Cordner, Hernandez, Jewel, O'Henry and NC Porto Rico 198. The O'Henry is the only white one in the bunch.)

White sweet potatoes are generally sweeter than the orange variety, although they are also perceived to have a milder flavor. Some people consider the whites to be drier and “mealier” than the orange. This is especially true among marketing people from Louisiana. The white potato has a softer skin than the orange, which also has a firmer, denser texture. You can tell them apart at a glance; “white” sweet potatoes have lighter skins, “orange” sweet potatoes are darker. Both are very nutritious, but the orange variety obviously has more beta carotene.

All that said, neither white nor orange sweet potatoes are truly “yams.” So if you think you've been serving candied yams at Thanksgiving all these years, you really haven't. Thanks to brilliant marketing out of Baton Rouge, they've actually been candied sweet potatoes. And an “Iron Chef” should really know the difference. I'm only a lowly “Aluminum Foil Cook” and I know. And now so do you.