How sweet potatoes rose to popularity at Thanksgiving

Sweet potatoes have become one of the most popular side dishes at Thanksgiving, but the roots may also be one of the least authentic of the common Thanksgiving foods.

The Wampanoag and Plymouth colonists who shared a feast in 1621 were familiar with turkeys, cranberries and pumpkins. They did not, however, have sweet potatoes, which only became part of Thanksgiving celebrations in the late 19th century.

The sweet potato was first domesticated in southern Mexico or Central America at least 5,000 years ago. It is not a nightshade and is only distantly related to the white potato, which was first domesticated in Peru perhaps 10,000 years ago. 

The Spanish conquerors took the sweet potato back to Europe. In the 16th century, it was regarded as a strong aphrodisiac, including by that century’s two most famous English gluttons Henry VIII and Shakespeare’s fictitious Sir John Falstaff.

Sweet potatoes got to the U.S. through European immigrants. Several hundred years before Columbus, the sweet potato made it across the Pacific Ocean to Polynesia. Evidence includes radiocarbon dating and genetic testing, and most intriguingly, the Polynesian word for sweet potato resembles the South American word camote. It is remarkable to think of people crossing the Pacific Ocean a thousand years ago carrying sweet potatoes in tiny canoes.

Sweet potatoes are frequently mislabeled as yams in the United States by marketers wishing to distinguish those with orange flesh from paler ones. A true yam, a root found in Africa, is botanically different from a sweet potato, and is rarely sold in the U.S.

Sweet potatoes and white potatoes vie for leadership at Thanksgiving, although both are among the most popular side dishes. Sweet potatoes are the more nutritious choice, as they have almost twice the antioxidant value of white potatoes and a much lower glycemic index.

Baking sweet potatoes makes the most sense for Thanksgiving because they can be placed in the same oven as the turkey. An added benefit, baking doubles the already high antioxidant value.

Another benefit of baking is that the baked skin is more nutritious than the flesh. This is also a reason to buy from our local growers who can be trusted not to grow them in chemical-infested soil.

However, I believe that most sweet potatoes served at Thanksgiving are mashed into casseroles. This can be more festive-looking and prepared in advance.

Microwave until soft and mash two sweet potatoes in a large bowl. Most recipes call for cubing sweet potatoes and boiling them in water until soft, as is done for mashed white potatoes. However, boiling sweet potatoes reduces their nutrient value. Better to bake or microwave them until soft.

Mix until smooth the cooked mashed potato, 1 egg, ¼ cup sugar, ¼ cup milk, 2 tablespoons softened butter, ¼ teaspoon vanilla extract and ¼ teaspoon salt. Transfer to a 6-by-9 inch baking dish.

An allrecipes.com recipe suggests adding a pecan topping. In a bowl, mix together ¼ cup brown sugar, 3 tablespoons flour, 2 tablespoons softened butter and ¼ cup chopped pecans. Sprinkle over the sweet potato mixture. Bake at 325 degrees for 30 minutes.

Melting marshmallows atop the sweet potato mixture is a popular topping, but sweet potatoes are already sweet, and so is dessert. A marshmallow topping could cause a sugar overload. On the other hand, a marshmallow topping might get vegetable-averse family members to eat the sweet potatoes.

James Rubenstein is president of the Board of Directors for the Oxford Free Press and professor emeritus of geography at Miami University.