What you see on the shelf labled as a red garnet or jewel yam is actually a sweet potato, botanically speaking. It’s not really a yam but it was given that name after a variety of sweet potato introduced to the U.S. in the mid 20th century. The name was used to distinguish it from the drie, paler, cream-flesheded sweet potato that most people were accustomed to at the time. This whiter sweet potato is sweet and starchy like the red “yams.”
In contrast, true yams are starchy, earthy, hardy flavor and texture. They are not sweet. They belong to the Dioscoreae family of tubers native to Asia. You can buy dried dioscorea root (cut int thin oblong pieces) in Chinese and Japanese markets and Chinese herb stores. I powder and use this to replace oats or oatmeal in meatballs and meatloaf. I bring this up to give you an idea of how different true yams are to sweet potatoes and what we, in the U.S., have come to associate with when we see the word “yam.”
According to information in an article entiteld “Sweet Potatoes The Healthy and Anti-Diabetice Starch” on Dr. Michael Murray’s web site, “Sweet potatoes are native to Central America and are one of the oldest vegetables known to man. They have been consumed since prehistoric times as evidenced by sweet potato relics dating back 10,000 years that have been discovered in Peruvian caves.
The spread of sweet potatoes
“Christopher Columbus brought sweet potatoes to Europe after his first voyage to the New World in 1492. By the 16th century, they were brought to the Philippines by Spanish explorers and to Africa, India, Indonesia and southern Asia by the Portuguese. Around this same time, sweet potatoes began to be cultivated in the southern United States, where they still remain a staple food in the traditional cuisine.
"In the mid-20th century, the orange-fleshed sweet potato was introduced to the United States and given the name "yam" to distinguish it from other sweet potatoes. Sweet potatoes are a featured food in many Asian and Latin American cultures. Today, the main commercial producers of sweet potatoes include China, Indonesia, Vietnam, Japan, India and Uganda.”
What’s in it for you?
The nutrient these vegetables are most known for is their high carotene content. The darker the variety of sweet potato, the higher the concentration of carotenes. So red garnet “yams” pack more carotenes then Jewel “yams” or white sweet potatoes. A single cup of cooked sweet potatoes contains 30 milligrams of beta carotene. (Don’t assume that automatically converts to vitamin A though. There is some evidence that many people are unable to convert betacarotene into vitamin A or convert only a small amount.)
Deeper, darker red sweet potatoes (what we usually see labeled as red garnet yams) also contain the antioxidant lycopene (also found in tomatoes and watermelon). These compounds have been shown to be protective against many cancers, including breast, colon, lung, skin, and prostate cancer and to lower the risk of heart disease, cataracts, and macular degeneration neutralizing harmful oxygen free radicals before they can do damage our cells.
Move over oranges, make way for sweet potatoes
Sweet potatoes also contain generous amounts of vitamin C and vitamin B6 along with lesser amounts of manganese, copper, biotin, pantothenic acid, vitamin B2, and dietary fiber.
Beyond the blood sugar blues
“Unlike many other starchy vegetables, sweet potatoes are classified as an ‘antidiabetic’ food," says Dr. Murray who cites animal studies that showed that sweet potato helped stabilize blood sugar levels and improve the response to the hormone insulin. White-skinned sweet potato (Ipomoea batatas) appear to be more effective here than red-skinned varieties. In a human study, consumption of white sweet potato consistently improved metabolic control in type II diabetic patients by decreasing insulin resistance.
Selecting and storing sweet potatoes
Sweet potatoes and what we see labeled as yams in American supermarkets should all be firm, smooth, and umblemished. Avoid wilted, leathery, or discolored sweet potatoes especially those with a green tint, soft spots, or moldy ends.
Look for narrow tubers that are no larger around than what you can wrap your hand around, touching your thumb and forefinger. Jumbo sweet potatoes with a wide diameter tend to be tough and mealy so I usually avoid them.
Store sweet potatoes at room temperature in a basket, bowl, on a rack with some room for air to circulate. If stored in a bowl or basket, check often to avoid spoilage. I usually buy six or more at a time. If you’re cooking for two or three people and you eat them several times a week you may want to buy them by the dozen.
Note: If stored in quantity, separate each sweet potato with crumpled newspaper to keep moisture from collecting on the skin, which can invite mold. Do not refrigerate uncooked sweet potatoes or yams. Sweet potatoes should be stored in a cool, dark, and well-ventilated place where they will keep fresh for weeks. They should be stored loose and not kept in a plastic bag. Keep them away from exposur e to bright sunlight (read: don’t store them on a windowsil) and temperatures above 60 degrees F since this will cause them to sprout and/or ferment.
Tips for Preparing
If you purchase organically grown sweet potatoes, you can eat the entire tuber, flesh and skin. Yet, if you buy conventionally grown ones, you should peel them before eating since sometimes the skin is treated with dye or wax; if preparing the sweet potato whole, just peel it after cooking. I find even the organic ones often have tough skins or have a slightly modly unpleasant taste, so I usually peel before cooking (if slicing) or after cooking (if baking them whole).
Because the flesh of sweet potatoes will start to oxidize upon contact with air, you should cook them immediately after peeling and/or cutting. If this is not possible, to prevent oxidation, keep them in a bowl covered completely with water until you are ready to cook them or, if making sweet potato fries, toss them with fat or oil (the fat or oil you plan to roast them in) to evenly coat. Wait to add sea salt until just before cooking lest they weep and sit in a puddle of water, which will dilute the flavor and prevent caramelization during cooking.
Try it, you’ll like it
Here’s a family-friendly recipe that’s been popular with children and adults. It’s been a huge hit in my online and on ground cooking classes for years and with friends. It’s from my cookbook, The Garden of Eating: A Produce-Dominated Diet & Cookbook. To read more about and order the book, click here.
Here’s a video of me making Roasted Sweet Potato Fries from my cooking dvd:
Silver Dollar Sweet Potatoes
Prep: 30 minutes/ Cooking: 45 minutes /Yield: 6 servings
Don’t wait for the holidays to serve sweet potatoes. They’re delicious all year round and handy for pack lunches or quick meals at home. These mouthwatering medallions are rich in potassium and beta-carotene and lower in fat and sodium than French fries. The aroma during baking or reheating under the broiler is reminiscent of oatmeal cookies or cinnamon toast. People who don’t usually like sweet potatoes or yams usually like these.
Source: The Garden of Eating: A Produce-Dominated Diet & Cookbook by Rachel Albert and Don Matesz. To read about and order your copy, click here for the best price on the internet.
2 tablespoons ghee, melted, unrefined coconut oil or avocado oil
2 teaspoons apple pie spice or ground cinnamon or dried, powdered rosemary
4 large or 6 medium sweet potatoes or yams (2 to 2 1/2 pounds):
Jersey sweets, white sweet potatoes, beauregard, or Japanese sweet potatoes, or red garnet or jewel yams
1/2 teaspoon finely ground, unrefined sea salt, optional
- Preheat oven to 400˚ F. Measure out the fat or oil and the spice and set aside.
- Rinse and scrub sweet potatoes with bristle brush. Pat dry. Remove rough sections and any soft or black spots. Peel if desired. Cut into 1/3-inch thick rounds with sturdy vegetable or chef knife or use a mandoline for potato chip-like texture. Cut into 1/2-inch thick rounds for softer, French fry-like texture.
- Place the sweet potato slices in a large bowl and toss with the fat or oil to coat well. Sprinkle on the spice and optional sea salt and toss to coat. Arrange vegetable slices one layer deep on 2 to 3 large, liberally greased cookie sheets or shallow baking pans. (For easy cleanup, line them with unbleached parchment paper.)
- Bake for about 20 minutes minutes. Flip the vegetables with a metal spatula if desired, and bake for another 15 to 20 minutes or until tender and lightly browned. For crisper slices, raise the heat to 450˚F during the last 10 minutes of cooking. Serve while warm. Refrigerate leftovers and use within 3 days, reheating them in an oven or toaster oven for about 10 minutes.
1 serving: 205 calories, 3 g protein, 38 g carbohydrate (4 g fiber), 5 g fat, 52 mg calcium, 15 mg sodium
- Baked Spiced Sweet Potato Halves: Cut raw sweet potatoes in half lengthwise. Rub or brush cut sides with oil or ghee and dust with pie spice or cinnamon. Rub 2 spiced halves together to spread seasonings. Place cut side down on baking sheet lined with unbleached parchment for ease of clean up. Bake until bottom side is golden brown and tubers are tender when poked with skewer, 20 to 40 minutes, depending on size.
- Roasted Sweet Potato Fries: Cut the sweet potatoes into french fry like sticks and prepare as directed above, turning them over after 25 minutes of cooking.
Source: The Garden of Eating: A Produce-Dominated Diet & Cookbook by Rachel Albert and Don Matesz. To read about and order your copy, click here.