The purple yams you find in the grocery store are usually from the family of sweet potatoes — the orange variety — rather than yams. Baked purple sweet potatoes make a delicious side dish that can boost your health by reducing inflammation and oxidative stress.
Bake purple yams just as you would do with sweet potatoes. Peel and roast them in a preheated 375 degrees Fahrenheit oven with a little oil, salt and pepper.
What Are Purple Sweet Potatoes?
All sweet potatoes come from the morning glory family, states Harvard Medical School. These roots differ from yams, which are edible, starchy tubers. In fact, they are not "potatoes" at all. White potatoes, such as Russet or Idaho, belong to the nightshade family and have a different botanical makeup.
Stokes purple sweet potatoes are a variety of purple-skinned and purple-fleshed potatoes originating in North Carolina. They are dense and tend to be slightly drier in texture than orange types of sweet potato. You may also find other varieties of purple sweet potatoes. These include the following:
- Okinawan, which is beige on the outside and lavender-colored on this inside. They have a creamy texture and are a standard ingredient in the Hawaiian pie called Haupia. Use them in this recipe from LIVESTRONG.com: Purple Sweet Potato Hummus.
- Murasaki sweet potatoes, or Japanese sweet potatoes, are white on the inside but have purple skin.
- Ube is, in fact, a yam that's purple inside and brown on the outside. Due to their naturally sweet flavor, they are a common ingredient in Asian desserts.
All of these varieties can be baked or steamed the same way.
Purple Sweet Potato Nutrition Facts
Harvard Medical School explains that purple sweet potatoes contain a unique phytochemical known as anthocyanin.
BioMed Research International published a review in October 2015, showing that the phenolic compounds, flavonoids and anthocyanins in purple sweet potatoes exhibit anti-inflammatory and anti-cancer effects. Anthocyanins also boast anti-diabetic and antimicrobial properties.
The University of California notes that a cup of cooked purple sweet potato contains about 500 milligrams of anthocyanins — close to the same amount in a cup of blueberries.
Frieda's — a major marketer of Stokes sweet potatoes — notes that a 3.8-ounce serving provides 130 calories, 28 grams of carbohydrates, and 2 grams of protein. You'll also get 2 percent of the daily value for vitamin A and 20 percent of the daily value for vitamin C as well as some iron and calcium.
Compare this to an average sweet potato that, according to the USDA, boasts 127 calories, 23.5 grams of carbohydrates, 2.3 grams of protein, and 3 grams of fat in a 4.1-ounce serving. These starches do have a similar nutritional value, but sweet potatoes are higher in antioxidants and other bioactive compounds.
Read more: Sweet Potatoes and Weight Loss
Baking a Purple Sweet Potato
Unlike their orange cousins that are often adorned with brown sugar, marshmallow or maple syrup, purple sweet potatoes are delicious on their own — with just a little butter, salt and pepper.
The University of California suggests you bake purple sweet potatoes after washing and scrubbing them well. Place in an oven preheated at 375 F until tender. For most average-sized potatoes, this takes about one hour.
When the potatoes are soft, split them open and top with a small dollop of butter and seasoning. You may also enjoy them with an added squeeze of lime juice and chopped fresh cilantro.
When you use purple sweet potatoes in baked goods, such as quick bread or cakes, the anthocyanins responsible for their color may react with baking soda and baking powder, giving them a blue or green hue. Sometimes, these antioxidants can turn your baked goods red, explains Maryland Grows.
- University of Maryland: "Baking, Chemistry, and Purple Sweet Potatoes"
- Harvard Medical School: "Sweet Potatoes"
- University of California: "Why Purple Sweet Potatoes Belong on Your Holiday Table"
- American Sweet Potato: "Yam vs. Sweet Potato"
- Biomed Research International: "Anti-Inflammatory and Anticancer Activities of Taiwanese Purple-Fleshed Sweet Potatoes (Ipomoea batatas L. Lam) Extracts"
- Frieda's: "Stokes Sweet Potato"
- USDA: "Sweet Potato"
- Carnegie Museum of Natural History: "Potatoes, Sweet Potatoes and Yams: What's the Difference?"
- Frieda's: "The Ultimate Purple Sweet Potato Guide"
- FoodNetwork.com: Candied Yam Souffle