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What the heck is Konnyaku?

Konnyaku (こんにゃく) is a rubbery and somewhat flavorless food that appears in certain Japanese dishes. It has a consistency that’s like a cross between a rubber sole and Jell-O that gives your teeth a funny sensation when you bite into it.


I was eating it the other day in a bowl of oden (おでん – a type of Japanese stew) and it occurred to me that I had no idea what it was. Is it a fish? Is it some kind of vegetable pulp or gelatinized seaweed?

It turns out that konnyaku is a jelly made from a type of potato. The potato in question is known in English as konjac (its scientific name is amorphallus konjac – definitely doesn’t sound like something you want to eat).

Konnyaku is a taro-like potato that grows in tropical and sub-tropical Asia. Almost all of Japan’s konnyaku comes from the northern Kanto region and Gunma Prefecture in particular. Other colorful names for the potato are devil’s tongue, voodoo lily, elephant foot and snake palm.

How Konnyaku Goes from Potato to Wobbly Slab

I’ve never made my own konnyaku, but from what several octogenarians in my neighborhood have told me, it goes something like this. The potato is warmed and softened and then mixed with water. Once the mixing is complete, it’s dried out and ground. It’s then mixed with ash from burnt green oak wood to give it its stiff consistency. Then, it’s patted into shape and boiled.

comes in several different forms. It’s most often found as a thick grey slab called itakonnyaku (いたこんにゃく). It also comes in stringy noodles which can be either the thin shirakonnyaku (しらこんにゃく) or itokonnyaku (糸こんにゃく), or the thick tsukikonnyaku (つきこんにゃく). Sometimes it’s rolled into little balls called tamakonnyaku (玉こんにゃく).

Konnyaku Japanese dish
Photo by avlxyz

Broom of the Stomach

Konnyaku in all its forms is extremely healthy. It’s high in a type of fiber called glucomannan that supposedly helps you lose weight. It has traces of starch and protein and almost no calories since so much of it is made up of water. It also may help to normalize cholesterol, blood sugar, and blood pressure.

The Japanese call it inohouki (胃のほうき – broom of the stomach) because it does a great job of cleaning out your small intestines. That’s secret code for ‘it makes you poo.’ It’s used for this purpose in Chinese medicine and that’s actually how it first came to Japan.

Konnyaku appears in oden, a type of Japanese stew filled with all kinds of goodies, and various types of soup. It’s also stir-fried and the thin stringy konnyaku is eaten as noodles, most notably in sukiyaki. It doesn’t have much flavor and it has a consistency that you either love or hate. I’m one of the konnyaku lovers.

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