Japanese Sweet Potato

Creamy, sweet and velvety, Japanese Sweet Potato (also known as satsumaimo) is umami rich and super healthy. This Japanese Yam is one of the most popular root vegetables in Japan in fall and winter. It's highly versatile! I’ll show you the best way to enjoy it with baked sweet potato recipe. Enjoy!

Japanese Sweet Potato

I love Japanese sweet potato. My great grandmother used to make a fire in her garden and throw Japanese sweet potatoes in to roast them. I enjoyed them with my brother and cousins when I was a kid. Many families in Japan enjoyed those baked Japanese sweet potatoes or yaki imo during the winter.

Japanese sweet potato has become even more popular in recent times as more people are discovering the health benefits of it, and how tasty and versatile it is.  

Baked sweet potato shops (yaki imo ya san) are popping up all over the place, and stylish food trucks are selling roasted Japanese sweet potatoes as street vendors.

I've decided to introduce you this magical Japanese sweet potato, and then I'll share the recipe. There are many ways to cook them, but I’m going to share my favourite Japanese sweet potato recipe. It's baked ones, and it's passed down from my mother, and her mother – so get on board the Japanese sweet potato train!

Bring joy into your life and share it with your loved ones. Read on!

What are Japanese sweet potatoes?

Potato in Japanese is called imo. Japanese sweet potatoes were brought from Okinawa (former Ryukyu Kingdom) to Satsuma in Kyushu, the southern part of Japan, in the 17th century. They were then called satsumaimo in Japan.

Recently, Japanese sweet potato has received much international attention for its distinct flavour – sweet, chestnut-like taste, with a silky smooth texture – delicious!

Nutrition and health benefits

Japanese sweet potatoes are packed with health benefits - rich in minerals, vitamins and fiber – they’re one of the healthiest vegetables you can find. (source)

They’re a staple in Okinawa, Japan's southern region. So perhaps it’s no coincidence that Okinawans enjoy one of highest life expectancies in the world.

It provides 264 calories per 200 grams (source):

• 2.4g protein
• 63g carbs (occupies 95% of the calories)
• 4.6g fiver
• 0.2g fat

Rich in vitamin B, and includes two antioxidant vitamin C and E.

Japanese sweet potatoes vs sweet potatoes

Also known as Japanese yam, Japanese sweet potatoes are cream-coloured inside. They turn into yellow sweet potatoes when you cook them. They are naturally sweet and have less moisture than regular sweet potatoes.

Recipes with Japanese sweet potato

You'll enjoy Japanese sweet potatoes. They are highly versatile, and can be simmered, baked and roasted as a main dish, snack or even used for sweets or dessert. The leaves, skins and stems are all edible. Here are some ideas for how to use Japanese sweet potatoes:

• Sweet potato fries (satumaimo no tempura)
• Satumaimo gohan (sweet potato rice)
• Pureed for a traditional New Year's dish (kuri kinton)

Japanese sweet potatoes as dessert:

• Baked Japanese sweet potatoes (yaki imo)
• Candied Japanese sweet potatoes (daigaku imo)
• Japanese sweet potato pie (sweet potato pai)
• Ice cream

These are popular Japanese sweet potato recipes in Japan.

Japanese sweet potatoes are sweetened naturally when you add heat. So the flavour and taste change dependent on the degree and amount of heat.

But I want to show you one of my favourite Japanese sweet potato dishes – baked Japanese sweet potatoes. Keep reading!

Where to buy Japanese sweet potatoes

You can easily find these sweet potatoes at Asian grocery stores during the fall and winter season. They’re also available at Trader Joes and Whole Foods in North America, and Woolworths in Australia.

How to pick up the best

Find firm, heavy sweet potatoes with fresh red violet coloured smooth skin. Avoid dried, spotted and wrinkled ones with hard roots. They are less sweetened and have excessive fiber. Dark coloured or black spots on the skin are often bitter, so avoid them as much as possible.

How to Cook Japanese sweet potatoes

Choose ripe sweet potatoes if you can. But these root potatoes are often not mature enough when they’re harvested and put on the shelf for sale.

If they’re not completely ripe, leave them in the kitchen for two weeks before using. This will allow them to develop more sweetness.

They can keep for up to a month at room temperature if you don't use them straight away. Avoid direct sunlight.

How to Bake Japanese Sweet Potatoes in the Oven

These root vegetables are best enjoyed when they are baked (roasted). All you need to do is thoroughly clean them with running water, and soak them in water for an hour.

Then wrap each of them with kitchen paper, and cover with foil. Put them into the oven at 320 F degree (160 C degree) and bake.

I like to keep the Japanese sweet potatoes moist. To do this, wrap them in wet kitchen paper before wrapping them in foil. This will steam them slightly, keeping them moist.

There’s no need to make holes with a fork over the skin. It actually takes more time to bake when you do this, and has no improvement to the result. There’s also no need to preheat the oven.

The best temperature for cooking Japanese yam

I tested cooking them at various temperatures. I've found that cooking them at lower heat for longer results in more natural sweetness and a softer velvety texture. When it's baked with a high heat for shorter, it’s less sweet and the texture is more solid.

So, for ideal results, cook them at 320 F degree (160 C degree) for 90 minutes. This is similar to how my great grandmother cooked them – throwing them into the fire embers, and leaving them in the ash to cook for a long time.

But more than 90 minutes is not recommended as they become dry. You’ll know they’re ready if the inside is soft when you stick a skewer in them. Leave them in the oven for a while.

If the inside is soft when you skewer them, it's ready. Turn off, and leave them in the oven for 30 minutes. This will increase the sweetness.

If your sweet potato is really big and a bit too thick for baking, cut it into half and place wet kitchen paper the flesh side, then wrap with foil. This avoids the foil sticking on the flesh surface as it cooks.

That's it! Serve immediately. Enjoy!

FAQs

How long do Japanese sweet potatoes last

As soon as you bring them home from the shop, wrap them in newspaper, and leave them at room temperature for up to a month. Avoid direct sunshine.

How to save baked Japanese sweet potato

For baked sweet potatoes, it's not recommended to save at room temperature. Wrap them up individually with plastic film, and keep them in an air-tight container or ziploc bag in the fridge for four days.

How to freeze baked Japanese sweet potato

Wrap them up individually with plastic film, and keep them in an air tight container or freezer bag in the freezer for one month.

How to eat Japanese sweet potatoes

Enjoy Japanese baked potatoes on their own. The skin is edible but I peel it off. You can also enjoy them with sour cream, butter, honey and more.

Can you eat skin of Japanese sweet potato?

Yes. You can eat the skin. Avoid dark coloured or black spots on the skin and on they inside. They bring bitterness.

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