Comparing Japanese Yellow Sweet Potato Paste Snacks by Specialists: Wakasayahonpo's Potato House and Unagiimo

I love the combination of sweet potatoes and tarts, and got 2 varieties of yellow sweet potato paste tarts to try and compare. [I have previously reviewed the Okinawan Purple Sweet Potato (Beni-imo) Tart and a Macau-inspired Portuguese Purple Sweet Potato Taro Egg Tart, both of which I loved. I also tried a Yellow Sweet Potato and Apple Tart by Foucher Paris, which I didn't like.]

The first was the Unagi-imo Tart, followed by the Hokkaido Jaga Butter Sweet Potato. Both of them have very premium and pure ingredients and were overall great gourmet snacks. But I preferred one over the other.

"My Sweet" Unagi-imo Tart by Unagiimo Store

Unagiimo is a special variety of the yellow satsumaimo grown in Hamamatsu, Shizuoka. Hamamatsu is known for growing unagi (eel), and they started using unused eel parts as fertilisers for their satsumaimo to avoid wastage, hence they call it unagi-imo. (They apparently refined the fertiliser until they were happy with the results.) They claim that the resulting unagi-imo has "umami" elements, which is the 6th taste that monosodium glutamate (MSG) is supposed to stimulate, and it is apparently also found in higher quantity in seafood, which is why broths made from seafood such as clams and prawns taste so good. It was sold by the official Unagiimo Store. (The individual wrapper is the bottom right one in the image below.)

Taste-wise, I actually did not notice anything umami or savoury about it. Conversely, what stood out to me were the very strong honey and floral notes in the sweet potato paste. (It was in sharp contrast to the Jaga Butter one below which was more savoury.) There was a small hint of earthy sweet potato notes, but it was mostly dominated by the honey flavour. 

There was also a strong caramelised flavour, similar to a candied sweet potato or chestnut. The caramelised notes blended well with the tart crust to come across similarly to a buttery florentine crust. Maybe this aspect was the closest I could imagine to an "umami" taste (but I attribute it more to the crust than the sweet potato paste.)

The ingredients list included mirin and liquor, interestingly, which probably accounted for the strong honey and caramel notes. (See image below.)

Texture wise, it was a normal pastey tart. It was not dry, but it did not come across as particularly moist or buttery either.

Finally, here are some images with the ingredients list (click to enlarge image - it is the bottom right wrapper) and the other unagi-imo products that were packed in a variety pack, very suitable for gift giving. The main ingredients are satsuma-imo, sugar, flour, butter, egg, liquor and mirin. Very pure. I think some salt would have enhanced the overall taste, however.

Hokkaido Potato Jaga Butter Sweet Potato by Wakasayahonpo's Potato House

The next was Hokkaido Potato "Jaga Butter Sweet Potato" by Wakasayahonpo's Potato House. To be accurate, I tried the pure paste version, but they also sell the tart version with a proper crust. I bought this in Singapore from a Japanese retailer.

Curiously, it is more of a potato paste tart with added sweet potato. Its name Jaga Butter actually means potato butter (sweet potato is always called "imo" instead of "jaga" in Japanese). And it actually tasted like the sweet potato version of mashed potatoes, in a really great way. This was meant to be eaten with a spoon apparently as there is no tart crust, but I didn't know and treated it like a tart, digging it out whole and reheating it in the oven.

It was like a very moist and dense or fudgy cake, but one that was not cloying or sweet, and remained soft even after oven reheating. As mentioned, the best comparison is mashed sweet potatoes. It was very very buttery and creamy, with notes of condensed milk, although that was not in the ingredients list. A tinge of salt balanced it well.

There were slight earthy notes from the sweet potatoes, but they blended well with the creamy buttery taste, similar to the case of mash potatoes.

The creamy buttery taste was probably especially strong because they used cultured butter, which is a premium version of butter commonly used in gourmet snacks in Japan to enhance the buttery flavour. 

There was apparently liquor used too (in the ingredients list below), but I could not discern its taste in the mix.

When I examined the ingredients list (click to enlarge image), it turns out that they did indeed use more of actual potatoes (in 2 different forms), in addition to the sweet potatoes, so the name is actually accurate. The first ingredient is a potato paste, which also mixes in some white bean paste and salt. Followed by: sugar, roasted sweet potato paste, cultured (or fermented butter), egg, milk, dairy products, dried mash potato (again!), liquor (interesting!), salt, sorbitol, etc. No shortening or margarine, which is great.

Overall verdict

I felt that the taste balance of Jaga Butter Sweet Potato was much better. The blend of potatoes and sweet potatoes and addition of salt helped to balance the creaminess and sweetness with earthy and savoury notes. Furthermore, the thoughtful choice of cultured butter probably made it more umami than unagi-imo, ironically. It was a very comforting and hearty snack.

The Unagi-imo Tart was unique for the intensity of the floral notes, but it was too cloyingly sweet and one-dimensional in that sense, so it was interesting to try, but might not be something I would try again. The packaging makes for a nice gift, though.

Discover other interesting tarts

• (mentioned earlier) Okinawan Purple Sweet Potato (Beni-imo) Tart
• (mentioned earlier) Macau-inspired Portuguese Purple Sweet Potato Taro Egg Tart
• Taiwanese Savoury Macadamia Tart by Shang Shin Select
• Salted Egg Yolk Golden Lava Egg Tart

Other interesting sweet potato snacks

• Suddenly Dumplings: Purple Sweet Potato Chocolate with Mochi and Bean Paste
• Annou Satsumaimo Sweet Potato "Oimo Financier" by Imokawa and Minamimachi Coffee, Tokyo
• Purple Sweet Potato Latte
• Purple Sweet Potato Macrobiotic Cookies (along with carrot, pumpkin, gobo and mug wort cookies)
• Japanese Sweet Potato Paste Snacks (custard ball and baked)