How can I make sure my sweetpotatoes are sweet? ASK THE HORT AGENT
Question How can I make sure my sweetpotatoes are sweet?
Answer I don’t know what makes an Irish potato Irish, but I do know what makes a sweetpotato sweet. There are three ways to increase or decrease the sweetness of a sweetpotato.
The first way to increase sweetness is by choosing a sweet variety. Researchers at North Carolina State University have a breeding program which focuses on producing better taters. Two of the current favorites are Covington and Beauregard (the latter is as popular as the Confederate general it was named after). Some folks say these varieties are also the reason we still have a breeding program (more work needs to be done).
While varietal differences can be subjective, the effect of curing is clear cut. Cured roots have higher levels of sugars and less starch than roots baked immediately after harvest. For best results, expose the roots to 85 degrees F and 90% humidity for one week. With the use of air conditioning, these conditions are hard to find. A sun room, attic, unused greenhouse or the trunk of your car could be possible solutions. Cover the taters if a sunny place is used. Extend the curing time if the humidity and/or temperature are not high enough. No curing will occur at temperatures below 70 degrees. After curing, store the taters at 55 to 60 degrees in a dry place, such as a basement, garage or pantry. Do not store in the refrigerator, where they may develop a hard core and an “off” taste.
The last way to affect sweetness is through cooking. When sweetpotatoes are cooked, activity of the amylase enzyme is initiated causing a conversion of starch to sugar. However, this process is affected by temperature and time. Like the baby bear’s porridge, it has to be just right. In lieu of a detailed explanation, here is the best way to bake a sweetpotato.
Place the taters on a pan in a cold oven. Set the temperature between 375 and 400 degrees. Cut the oven on. Remove the taters when they are soft to the touch (approx. 45 min).
If you microwave them, use a defrost setting as opposed to high power (6 to 8 min.). Microwaved, boiled or steamed potatoes will not be as sweet as baked potatoes. It’s all due to the starch conversion process.
Irish potatoes are in the same family as tomatoes, eggplants and peppers. Sweetpotatoes are in the morning glory (vine) family. Since Irish potatoes and sweetpotatoes are not related, the cooking of these roots also differs. Only sweetpotatoes convert starch to sugar. Ironically, sweet taters are also being studied as a treatment for type 2 diabetes (caiapo is the chemical and it is found in the tater skin).
If you pick a sweet variety, cure it properly and bake it slowly, then you won’t need to cover it with brown sugar. For more info on sweetpotatoes, visit http://www.ncsu.edu/featured-stories/innovation-discovery/nov-2007/sweet-potatoes/index.php If you don’t have internet access, call the Extension Office at 893-7530 or email me at gpierce@harnett.org
The word yam comes from the African word “nyami.” A yam is no kin to a sweetpotato or Irish potato. We know Popeye was no sweet tater cause he always said, “I yam what I yam. I’m Popeye the Sailor man.”
Gary L. Pierce
Horticulture Extension Agent
Harnett County | 
