What Are Japanese Sweet Potatoes?

Japanese sweet potatoes, or satsumaimo in Japanese, are a sweet, starchy root vegetable with reddish-purple skin and pale yellow to white flesh. Like other sweet potatoes, they originate in Central and South America, but this variety is typically associated with Japanese cuisine.

What Are Japanese Sweet Potatoes?

In addition to their color, what sets Japanese sweet potatoes apart from their orange-fleshed relatives is their texture. Because they’re a little drier and starchier than other varieties, Japanese sweet potatoes have a distinct creaminess and a fluffier, lighter texture, a little more like a regular baking potato than a standard orange sweet potato. They also have a particularly sweet yet, subtle flavor compared to many other varieties.

Sweet potatoes were introduced to China in the 16th century and then to Japan in the 17th century. There, Japanese sweet potatoes are often roasted whole and enjoyed as a standalone street snack, particularly when the crop is in season in fall and winter. They’re also mashed or pureed and served with candied chestnuts in kuri kinton, a traditional New Year’s dish.

How to Use Japanese Sweet Potatoes

Japanese sweet potatoes can be swapped in for orange-fleshed sweet potatoes in just about any recipe or application, such as steaming, boiling, roasting, frying, mashing, and pureeing. They make excellent sweet potato fries and bake up well whole or incorporated into casseroles and gratins. Because they hold their shape, they’re also excellent sliced into cubes, rounds, or chunks and roasted.

Due to the difference in texture, you may want to add a little extra moisture to a recipe usually made with softer sweet potatoes to create a smooth texture—for example, adding a little more liquid to a pureed sweet potato soup.

The skin of Japanese sweet potatoes is edible. Japanese sweet potatoes can be peeled before using, but they’re often prepared with the tender, nutritious skin on when baked or roasted. 

What Does It Taste Like?

Japanese sweet potatoes have a concentrated yet natural sweetness that’s earthier and nuttier than that of other sweet potatoes. They’re also lighter and fluffier in texture, thanks to their starchiness and low moisture content.

Japanese Sweet Potatoes vs. Sweet Potatoes

In addition to differences in flavor and texture, Japanese sweet potatoes have reddish-purple skin and pale yellow flesh. This differs from common varieties like Beauregard, Jewel, and Garnet, which have orange skin and orange flesh.

Japanese sweet potatoes are also different from Okinawan sweet potatoes (also known as purple sweet potatoes), which have light brown skin and purple flesh. Despite the fact that they are sometimes referred to as yams in the United States, all sweet potatoes (Ipomoea batatas) are different from true yams (Dioscorea), which are bigger and not sweet, with rough brown skin and a starchy texture.

Japanese Sweet Potato Recipes

Japanese sweet potatoes can be used in place of other sweet potatoes, especially in recipes where their sweeter flavor would be perfect for the dish.

• Whole Baked Sweet Potatoes
• Mashed Sweet Potatoes
• Baked Sweet Potato Fries
  

Where to Buy Japanese Sweet Potatoes

Look for Japanese sweet potatoes in the produce section of well-stocked supermarkets, grocery stores, organic and natural food markets, and food co-ops. They can also be found at Asian supermarkets and many farmers’ markets.

When shopping for Japanese sweet potatoes, seek out specimens with taut, unblemished skin and plump, firm flesh. Avoid sweet potatoes with wrinkled ends, dark spots, moldy areas, or nicks.

Storage

Japanese sweet potatoes can last for up to a month when stored properly. Store them in a cool, dark, dry place, such as in a closed pantry or cupboard—if Japanese sweet potatoes are exposed to light, they’ll sprout. Avoid keeping them in the refrigerator, and avoid washing your sweet potatoes before storing, as introducing moisture to the skins can cause them to rot prematurely.

A temperature between 50 and 60 F is ideal, so avoid storing your Japanese sweet potatoes close to your oven. Since locations closer to the floor will stay cooler, keeping them in a well-ventilated bin or storage container on a low shelf often works well. If possible, keep your onions on a separate shelf or in a separate storage area, as the gases they emit can cause your Japanese sweet potatoes to sprout prematurely.

You’ll know when Japanese sweet potatoes go bad because the flesh will become soft and soggy, and the skin will turn brown or black. Even if only a portion of the sweet potato has begun to rot, the flavor of the whole tuber will be affected, so it’s best to discard the whole thing.

Nutrition and Benefits

Like other sweet potatoes, Japanese sweet potatoes are rich in dietary fiber, with a 130-gram serving containing 16 percent of the recommended daily allowance of fiber. They’re fat-free, low in sodium, and a good source of potassium. One serving also includes five grams of naturally occurring sugars and 26 grams of carbohydrates, about nine percent of the recommended daily allowance.

Japanese sweet potatoes are an excellent source of Vitamin A (in the form of beta carotene) and Vitamin C, both of which support good overall health.