It is the fall season and almost holiday time. There seems to be an abundance of information and recipes for using sweet potatoes this year.
One source may say sweet potatoes and the next yams. Many Americans have been making the mistake of calling sweet potatoes yams. There is a difference. But what is the difference?
Sweet potatoes and yams are not even related. They are two different species of root vegetables. They have very different backgrounds and uses.
Yams, lily family Dioscoreaceae, are native to Africa and Asia and other tropical regions. They are starchy tubers that have an almost black bark-like skin and white, purple or reddish flesh. Yams come in many varieties. The yam tubers can be small or grow five feet long.
The word yam comes from an African word which means to eat. Yams are of great importance as a food in many parts of the world as they keep for a long time in storage. It is valuable when food is scarce due to dry or wet conditions.
Yams are typically peeled, boiled, and mashed or dried and ground into a powder. The powder is used in porridge. Generally, they are not grown in the United States. Yams can be found in international markets, especially those that specialize in Caribbean or African foods.
The sweet potato is related to the morning glory family, Convolvulaceae. Americans have been calling the orange-fleshed sweet potato variety yam since colonial times when Africans saw similarities to the tuberous yam variety they knew.
Sweet potatoes in the United States come in two main varieties. One has a golden skin with a yellow or white flesh and a crumbly texture. The other has a copper skin with an orange flesh that is sweet and soft. Sweet potato varieties generally have the same tapered shape at the ends and are smaller than real yams.
The United States Department of Agriculture decided to label the orange sweet potato variety "yam" to differentiate it from the other white or yellow sweet potato varieties. So what you find in the supermarket labeled yam is really an orange sweet potato. Many times the sign or label will say both yam and sweet potato.
Both the yam and sweet potato are known as top-notch health foods. But they offer different health benefits and different culinary uses. Both are considered low-fat foods.
Sweet potatoes have a reputation as one of the most nutritious low-calorie foods. They are packed with vitamin A and contain high amounts of calcium, iron and vitamin E. Sweet potatoes also have more protein per serving than yams. They contain massive amounts of anti-inflammatory compounds that are important to people with arthritis, gout and other inflammation diseases.
Yams not only lack these anti-inflammatory nutrients, they contain a number of compounds that aggravate those conditions. They do, however, have healthy fats and omega-3 acids.
Both have very low glycemic indexes, which are good for people managing diabetes and also wanting to lose weight. They are loaded with potassium, magnesium and phosphorous as well as the trace minerals selenium, zinc and copper.
Are you serving sweet potatoes or yams for Thanksgiving?
Jo Ann Graham
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