Karen Cambre, Sharpe, Kenneth W.
News article for November 5, 2018
Sweet potatoes are a part of a traditional Thanksgiving meal and just in time, the new crop of sweet potatoes is coming to market. I have noticed sweet potatoes advertised in the paper and have also seen yams advertised as being fresh. So which one should you buy, sweet potatoes or yams?
I have eaten both and have always associated them as pretty much the same taste, texture and color. It turns out that they are the same, but they are not the same.
Sounds confusing, but tradition and marketing contribute to the confusion. Sweet potatoes are a member of the morning glory family; you may know morning glory as tie vines. They have the scientific name Ipomoea batatas. The true yams are unrelated. They are listed as Dioscorea batatas and are grown in tropical climates such as South America, Africa and the Caribbean.
The true yams are tubers or underground root parts that have brown to black skin that looks more like tree bark. There are a number of different varieties and some have tubers that range in size from small to quite large, up to 7 feet long and 130 pounds. That puts a new meaning to the term “jumbo”, which many people associate with bigger sized potatoes. The confusion comes from southerners who would differentiate between firm potatoes and soft potatoes when cooked. We call the softer potatoes yams and the term has been used interchangeably with good sweet potatoes for many years.
True yams are said to be softer and sweeter than our native sweet potatoes.
Sweet potatoes are not sweet when they are first dug. We refer to the fresh dug sweet potatoes as “green” potatoes. They have to go through a curing process to allow the starches to break down into sugar and then they will be sweet. This curing process can take 7-8 weeks to get the maximum sweetness when baked. Once the potatoes go through this process they are then sold as “cured”. I think that it is the cured Louisiana sweet potatoes that are moist and sweet when baked that were called “yams” by our forefathers.
In Louisiana the sweet potato harvest begins in August and will conclude in November. It is usually close to Thanksgiving before you can get cured potatoes. If you were to purchase a box of green or partially cured potatoes, you can hold them yourself and let them cure. Put them in as cool of a place as you can outside of the refrigerator. Ideally they should be stored at 55 to 60 degrees F at 85 to 95 percent humidity to cure. You can take a sample every few weeks and bake them to see if they are sweet yet.
Another key to getting a really sweet potato is it has to be baked in the oven. Microwaving sweet potatoes will cook them, but will not convert the starches to sugar. You need a slower cooking time. Once you have baked the sweet potatoes, you can refrigerate them and then reheat in the microwave to yam perfection.
The LSU AgCenter and the LSU College of Agriculture