The age-old question — what is the difference between sweet potatoes and yams?

Sweet potato D's Harvest
My husband’s 2018 harvest of Beauregard sweet potatoes 

We had some dear friends visiting with us recently and they had a suggestion for a Cooking Tip. I figured if they had an interest in this topic that some of you would also. So, for this week’s Cooking Tip is the age-old question – what is the difference between sweet potatoes and yams?

Before I discuss that question, I have an interesting tidbit I ran across during my research. Is it more proper to write “Sweet Potato” (two words) or “Sweetpotato” (one word)? I have always thought it should be two words. However, the International Potato Center writes it as one word to differentiate it from true potatoes. The North Carolina Sweetpotato Commission agrees and would like us all to adopt the one word spelling. (My spell checker does not agree, though!) I will use both spellings in the rest of this tip.

Despite the name, sweet potatoes are not related to the potato. Whereas potatoes are tubers, sweet potatoes are actually a root of a vine in the morning glory family. They are said to originate from either Central or South America. They are grown abundantly in the US, particularly in southern states. Since 1971, North Carolina has been the #1 sweet potato producing state in the United States.

There are many different varieties of sweet potatoes. Here is a link to chart listing almost 125 varieties. I suspect you will only find two or three different varieties in your supermarket. There are different ways to classify them but I find the following the most helpful. It classifies sweet potatoes grown in the US into two major types although there are different varieties among each type.

  1. Firm sweet potatoes – These have golden skin and pale flesh that remains firm when cooked. They were actually the first to be produced in the US and in our stores, they are commonly called sweet potatoes.
  2. Soft sweet potatoes – These have coppery skin and orange flesh that becomes creamy and fluffy when cooked. When this variety became available, stores needed to differentiate them from the firm variety. At that time, African slaves thought they were similar to yams that they had known in their home country and began calling them by that word. This was then picked up and even today they are commonly called yams. Some of my research indicated that the USDA requires stores to add “sweet potato” to the label if they use the word “yam.”

Although they are available year-round, their peak growing season is from fall through early winter. When picking one out, choose one with a smooth skin, firm ends and no soft spots. Avoid storing sweet potatoes in the refrigerator, which will produce a hard center and unpleasant taste. Rather, store them in a cool, dry, well ventilated container. For best results, store them in a basement or root cellar away from strong heat sources.

Yams are a totally different and unrelated tuber. They are related to the lily family. To understand the differences, refer to this chart I adapted from the North Carolina Sweetpotato Commission.

 

Sweetpotato

Yam

Taste Sweetpotatoes are almost always sweeter than yams. Starchier and more potato-like, usually not very sweet.
     
Appearance In the U.S. the majority of Sweetpotatoes sold are one of four appearances:

  • Rose color skin with orange flesh
  • Pale copper/tan skin with white flesh
  • Red skin, dry white flesh
  • Purple skin and flesh

All are more slender in appearance than a potato and have tapered ends; however each of these does have a different flavor profile.

Varies considerably. Some yams are the size and shape of small potatoes; others can grow up to 1.5m (5ft) in length and weigh over 100lbs (70kg).

 

Skins may be dark brown or light pink; insides white, yellow, purple, or pink.

What most of us probably think of as a typical sweet potato whether it is made into delightful fries or on your Thanksgiving table in a casserole is what the stores call yams – although as I mentioned, they should be called yams/sweet potatoes. What the store calls just sweet potato is probably not going to be what you want for a traditional sweet potato dish. Are you confused, yet? Don’t be – choose more by color of the skin and even the flesh if you can rather than the name.

Since 2006, a purple sweet potato has become available. The three main types in the US are:

  • Stokes Purple® sweet potatoes – These originated in the US and have purple-tinted skin with a very purple flesh that intensifies when cooked. They are a bit drier and denser than orange sweet potatoes. They are very high in anthocyanins, the antioxidant that gives it the purple color.
  • Okinawan sweet potatoes – These are said to originate from South America but then migrated to the Philippines, China and Japan. Their name comes from the fact when they made it to Japan, they were first grown on Okinawa, a Japanese island. They can also be found in Hawaii and are at times called Hawaiian sweet potatoes. They have beige skin and a lighter lavender flesh, which turns blueish purple when cooked. They are said to have a delicate, slightly sweet taste with a creamy and starch texture.
  • Ube – This is not really a sweet potato but a purple yam. It is a staple in the Philippines and is often used in Asian desserts. It has brown, bark-like skin with flesh that ranges from white with purple specks to lilac. Although it is said to have a sweet and nutty flavor, my husband and I never did develop a taste for it during our time in the Philippines.

Friedas.com has a fun video demonstrating the differences between these three.

I love sweet potatoes any way you cook them. Or, should I say I love yam/sweet potatoes since I strongly prefer the orange-fleshed variety. I have never tried purple sweet potatoes although as I mentioned, I have partaken of Ube – not something I wish to repeat. How about you? Have you tried them? Let me know.

The image shown at the top of this post is my husband’s harvest of Beauregard sweet potatoes from 2018. All I have to say is — DELICIOUS!