Got some tuber confusion? A yam and sweet potato may look similar on the outside but they are absolutely two different things. When you thought you were eating a yam, you were most likely be eating a sweet potato. Yup! Those candied yams you had last Thanksgiving were not yams at all.
Many Americans have been making the mistake of calling certain varieties of sweet potatoes “yams.” This is when you shouldn’t rely on grocery store labels all the time. Improve your tubers vocabulary today through the quick guide below:
|Scientific Name||Ipomoea batatas||Dioscorea Species|
|Plant Family||Morning glory (Convolvulaceae)||Yam (Dioscoroeaceae)|
|Origin||Tropical America||West Africa and Asia|
|Appearance||Smooth with thin skin. Pink-skinned ones come with orange flesh while golden-skinned ones have white flesh.||Rough and scaly. May be small or big. Skin may be light pink or dark brown and flesh may be purple, pink, white or yellow.|
|Shape||Short with tapered ends||Long and cylindrical|
|Availability||Grown in the US and China||Imported from Carribean|
|Cooking/Serving option||Boiled, mashed, grilled, roasted||Boiled, mashed, dried|
|Calories in 8-ounce serving||200 calories||150 calories|
See? Sweet potatoes and yams are two very different species of root vegetable. Let’s dig a little deeper so you can further understand the difference between sweet potatoes and yams.
Both yam and sweet potato are tuberous root vegetables that came from a flowering plant. But although they are both angiosperms, their similarity ends there. They are not related botanically so they don’t have a lot in common.
Yams are related to the family of lilies and grasses. They are monocots like onions which mean they have one embryonic seed leaf. They grow for six to ten months and their production requires high labor. Research says that yam is toxic when eaten raw as they contain dioscorin, tri-terpenes and diosgenin that can get your tongue itchy. The common African yam is the Dioscorea rotunda and Dioscorea cayenensis – the white yam and the yellow yam. Dioscorea alata is the Southeast Asian purple yam or winged yam and Dioscorea opposita is the Chines yam or Japanese Mountain yam.
Sweet potatoes belong to the Convolvulaceae family along with water spinach. They are dicots or plants with two embryonic seeds. These are cultivated in tropical regions and warm temperate areas with enough water to support tubers’ growth. Sweet potatoes do not tolerate frost and grows best at areas with average temperature of 24˚C. But although it requires abundant sunshine and warm temperature at night, it is sensitive to drought but is not tolerant to water-logging. Sweet potatoes are grown on different soils and they typically mature in two to nine months.
Origin and Availability
Sweet potatoes were originally from Central and South America. They are among the oldest vegetables known as they have been consumed since prehistoric times. Today, majority of sweet production comes from China. In the U.S., 40% of its sweet potatoes are grown in North Carolina. Statistics from Food and Agriculture Organization says that about 20,000 Tonnes of sweet potatoes are produced in New Zealand every year.
Yams are native to Asia and Africa. Although yams are grown all over the world, majority of the supply come from Africa. Because of this, yams can be hard to find and are not readily available in local groceries. You have a good chance of finding real yams at international and specialty markets.
The skin color of sweet potatoes varies from white to yellow, to orange, or red orange. They can be firm or soft. Although sweet potatoes have many varieties, only two main types are common in the U.S. – the golden skinned with white flesh and the copper skinned with orange flesh. The former has a crumbly texture while the latter is sweet and soft. Sweet potatoes are generally short and blocky with tapered ends. The orange-fleshed with red-brown-orange skin “yams” you see at the grocery are not real yams; these are Garnet, Jewel and Beauregard varieties of sweet potatoes.
Yams usually have dark brown or black bark-like skin with flesh in white, purple, or reddish pink. Its skin is rough and will be difficult to peel if you won’t heat them first. Yams have over 600 varieties and 95 percent of it are grown in Africa. Yams are long and cylindrical. Their size varies and can go as small as a potato or get big up to 60 kilograms.
Yams are starchier and drier like potatoes. According to the “Vegetables” book by James Peterson published by Ten Speed Press, yams have a bland flavor and they require more aggressive treatment that the common potatoes. They can be paired with spicy sauces, garlic, and chilies.
Sweet potatoes have richer flavor and creamier texture. The orange-fleshed sweet potatoes, in particular, are always sweeter than yams. The sweet flavor of sweet potatoes pairs well with salty and spicy ingredients.
Note, however, that both vegetables have versatile flavors and it can change depending on the serving preparation and method of cooking.
Preparation and Serving
Both yams and sweet potatoes may be baked, boiled, grilled, roasted, fried or cooked together with other ingredients. They don’t take a long time to prepare. Yams are typically peeled, washed and blanched for about 15 minutes in boiling water before being used. They can be made into side dishes, main dishes and desserts.
You can make sweet potato gratin and even sweet potato biscuits. Coat peeled and sliced sweet potatoes with brown sugar, fry it and serve in a skewer for a filling dessert. Yam may be combined with pork for a stir fry dish, or mashed and blended together with butternut squash to make a soup. Purple yam ice cream is a well-loved dessert in Okinawa, Japan.
Both sweet potato and yam are nutrient-dense foods. However, sweet potatoes tend to hold more nutrients than yams.
Sweet potatoes are rich in Vitamin A making them ideal for your vision. It also has plenty of antioxidants because of its Vitamin A and Vitamin C content. Sweet potatoes are a good source of fiber too and they can help stabilize blood sugar levels of diabetics because of their low glycemic index. Because of sweet potatoes’ supply of complex carbohydrates, they can provide you with energy.
The Vitamin A that is converted to beta-carotene in yams may not be as signifcant as those found on sweet potatoes but yams antioxidants are exceptional. This tuber is also an excellent source of B-complex vitamins. Other nutrients in yams include thiamin, folic acid, pantothenic acid and niacin. The beneficial minerals found in yams also include manganese, iron, potassium and copper that helps produce healthy red blood cells.
Check the table below to see the comparison of nutrition content for an 8-ounce serving of yam and sweet potato:
|Protein||5 grams||2 grams|
|Carbohydrates||45 grams||40 grams|
|Fiber||7.5 grams||5 grams|
|Vitamin A||270 % of daily requirement||1 % of daily requirement|
|Vitamin C||1% of daily requirement||4% of daily requirement|
|Calcium||7% of daily requirement||4% of daily requirement|
|Iron||8% of daily requirement||7% of daily requirement|
|Vitamin B6||34% of daily requirement|
|Phosphorus||15% of daily requirement|
|Manganese||50% of daily requirement|
Labeling confusion in US supermarkets
The yams you usually see in groceries are basically the soft varieties of sweet potatoes. The confusion started when soft varieties of sweet potatoes were commercially grown in the U.S. Before that, only the firm variety is available. Research says that it was the African slaves who called “soft” sweet potatoes ‘yams’ because of their similarity with the yams in Africa. Hence, soft sweet potatoes were known as yams to distinguish them from the firm sweet potatoes.
At present, however, the U.S. Department of Agriculture already required to also include the term “sweet potato” when they label such products as yam. Now if you really wish to eat the real yam, better search the international market and not your local grocery for it.
Overall, both are nutritious and economical food. As to which one you should buy and eat, that largely depends on the flavor and texture you prefer and the recipe you’re preparing. You may want to get to know the different kinds of potato and actually eat a real yam.
At the grocery, look over the label carefully. This guide should help you differentiate a yam and a sweet potato and confirm the veracity of grocery labels on sweet potatoes and sweet potato “yams.”
Whether you’re getting yams or sweet potatoes, select ones that are firm and with unwrinkled flesh. You need not store them in the refrigerator – just in a cool, dark and dry place.
With these information, you should now have a clear understanding of the difference between yams and sweet potatoes. Though yams don’t come close to the nutritional value and flavor of sweet potatoes, yams have a unique set of characteristics that make them undeserving of the frequent comparison with sweet potatoes.