Konnyaku (コンニャク)

Konnyaku (scientific name: Amorphophallus konjac) refers to an herb of the Araceae family or a food derived from the plant's bulb.

With konnyaku used as food in Japan, the People's Republic of China, Myanmar, and the Republic of Korea, only Japan among these countries has cultivated it as agricultural products and distributed them to the market. Gunma Prefecture, a major konnyaku producing area in Japan, accounts for 90% of domestic konnyaku production, followed by Tochigi Prefecture as the second and Ibaragi Prefecture as the third, so Kita Kanto (Northern Kanto) produces 97% of Japan's konnyaku.

Konnyaku as a plant

Konnyaku is also known as Konnyaku imo (Taro). It is a deciduous perennial plant of the Araceae family, whose scientific name is Amorphophallus konjac. The English name for it is Elephant foot. Konnyaku is believed to be native to India or the Indonesian Peninsula (near Viet Nam), widely distributed in Mainland Southeast Asia. The underground part is a flat, round corm, from which a leaf comes out. The stalk (in fact, a leafstalk) grows to about 1 m in height with the leaf pedately divided into leaflets, which spread out horizontally at the tip of the stalk. The leaflets are soft, shiny and oval-shaped.

Although the root gradually enlarges, it takes some period of time to grow enough to come into flowers. Under cultivation conditions, it take five to six years to make the root grow before it starts to produce its flowers. Sending out no leaf in flowering, the root dries out after that. The whole inflorescence reaches up to as high as 2 m. The florescence consists of a conic appendix growing upright on a so-called spadix and a horn-like spathe opening upward with the limb of the spathe (projecting part) recurving to the stem. The entire florescence is dark purple.

In spite of the strong bitterness of calcium oxalate in a raw konnyaku imo, removing the bitterness from it in some way makes konnyaku edible.

By the way, Yamakonnyaku (A. kiusianus or A. hirtus var. kiusianus), species related to konnyaku, grows wild in southern Shikoku, Kyushu, Nansei Islands and Taiwan.

Konnyaku as food

A food usually called konnyaku is the one made from glucomannan in konnyaku imo, a polysaccharide which is transformed into starch and then coagulated by adding alkali (calcium hydroxide is in common use or ash water was added), creating its unique texture. Once coagulated, konnyaku is insoluble in water and highly elastic. In addition, konnyaku is extremely low in calorie and rich in dietary fiber, so that konnyaku is popular as a diet food (a health food).

It has, until now, been necessary to boil konnyaku in a process called akunuki (literally, removal of harshness) before it is cooked in order to remove its unique odor, but some types of konnyaku can now be cooked without this process being performed.

Ingredients of konnyaku

Ninety-six or ninety-seven percent of konnyaku is water, and the major ingredient is glucomannan except for water. Glucomannan, also known as konnyaku mannan, is a kind of polysaccharide polymerized with a ratio of glucose to mannose of 2:3 or 1:2 with the difficulty to digest in a human's digestive tract, and is partly converted to fatty acids by coliform bacteria to take in. For this reason glucomannan, one of the lowest calorie foods (5 to 7 kcal per 100g), is often used as a raw food material in case of necessity to control the calorie intake. With a typical dietary fiber, glucomannan is also said to lower the level of sugar and cholesterol in blood and to enhance healthy immune function.

How to produce konnyaku

Konnyaku can be made by grinding corms into powder (in fact, two types of powder, roughly ground konnyaku corm powder and refined mannan powder, are mixed together in producing konnyaku), kneading the two types of powder with a little water to make konnyaku paste, adding milk of lime (a suspension of lime (here slaked lime) in a little water: an aqueous solution of calcium hydroxide) to the paste, boiling and solidifying it. Pure konnyaku, which is whitish-gray, is produced as a result, but the most typical konnyaku is another one that finely ground sea weed such as hijiki is added to pure konnyaku for the characteristic dark color before molding konnyaku. In addition, konnyaku in thread-like form is called ito konnyaku (konnyaku noodles), and the one formed more thinly than ito konnyaku is known as shirataki (literally, white waterfall). Omi Hachiman City produces aka konnyaku (red konnyaku) by adding iron sesquioxide that makes konnyaku red. Calcium oxalate contained in konnyaku plants requires great caution in processing konnyaku (ideally, rubber gloves should be put on).

It is believed that in 1776, Toemon NAKAJIMA (1745-1825), a farmer in Yamagata Town, Naka County, Mito Domain, conceived a bright idea of grinding dried konnyaku corms which he had found don't go bad, and then Myojitaito (the right to bear a surname and wear a sword) was awarded for his invention. Making pure konnyaku dark with some ground hijiki as a colorant powder is reminiscent of using grated konnyaku imo with its skin. In the Edo period, developing a new milling method made it possible to produce white konnyaku, whose bad reputation resulted in coloring konnyaku on purpose.

How to cook konnyaku

Konnyaku is mainly used as an ingredient in shirumono (a soup dish) and nabemono (a dish served in a pot at the table) such as oden (a Japanese dish containing all kinds of ingredients cooked in a special broth of soy source, sugar, sake, etc), nimono (food boiled and seasoned), miso soup, and pork miso soup. It is also served as miso dengaku (skewered and roasted konnyaku with miso coating). Ito konnyaku' or 'shirataki' is used in sukiyaki. Raw konnyaku is sometimes sliced thinly to serve as sashimi.

Tamakonnyaku (ball-shaped konnyaku)

Tamakonnyaku is the one that a few bite-sized pieces of tamakonnyaku are skewered on a disposal wooden chopstick, and the tamakonnyaku-on-skewers are simmered in a soy sauce based broth in a large pot. In Yamagata Prefecture, these skewers are always sold at sightseeing areas, festivals, and school festivals. Besides, some izakaya bars in Tokyo, featuring local dishes of Yamagata, introduce tamakonnyaku as their house specialty on the menu.

Tamakonnyaku is often served with mustard.

Simmering tamakonnyaku in a broth of surume (dried squid) and adding more of sake (rice wine) to the broth makes tamakonnyaku delicious to eat.

Tamakon,' short for Tamakonnyaku, is a registered trademark of Hiranoya Company (Yamagata Prefecture) ("registration number of brand name"No. 762418).

Konnyaku jelly

See konnyaku jelly for more information.

Konnyaku jelly is fruit jelly solidified by mixing konnyaku powder and fruit juice. With the feature that konnyaku is rich in dietary fiber, konnyaku jelly is advertised to be better for health, especially for a health diet, than jelly made from gelatin.

Waterproof high polymer materials

Flexible rubber and synthetic resin are used, for example, in order to water and air proof paper or cloth. During the World War II, however, Japan experienced the difficulty in procuring rubber from Southeast Asia and in mass-producing synthetic resin both technologically and economically. Being inferior to rubber in durability, konnyaku was easier to procure in Japan.

At that time, Konnyaku was frequently used as a waterproof material, showing high water and air resistance when applied to paper and cloth after boiled and melted. Konnyaku, which was originally used for making Japanese umbrellas as 'konnyaku adhesive,' found an application in producing weapons such as balloon bombs at the end of the war. Now, eco-friendly, biodegradable materials are selected for air proofing today's balloons, although they are not the saccharide polymer material which is the raw material of konnyaku imo.

Konnyaku used in a haunted house

Konnyaku is sometimes used as a fun item to frighten people in a haunted house or in a place of kimodameshi (a test of courage). Hung with a code, konnyaku is thrown at their faces or the back of their necks. With the chilly texture, it leaves indescribable creepy feeling to them.

Today this use of konnyaku, however, can be seen only in such an 'amateur entertainment 'as an event performed in some school festivals. The concept of 'mottainai' (wasteful) lies behind it because konnyaku is a food. Refrigerant gel or wet dish towels are used instead.

Images or words of konnyaku
Konnyaku, watery and soft, has an image of something both flexible and elastic.
There are some examples that something elusive is compared to konnyaku; as for baseball player, konnyaku-like batting style of Masataka NASHIDA and konnyaku-like pitching style of Masao SATO, or konnyaku tactics in a boxing manga (a comic), 'Ashita no Jo (Tomorrow's Joe).'

The diet member's league for the konnyaku industry in the Liberal Democratic Party

The activity of this league is to protect and foster farmers who cultivate konnyaku in Japan. Keizo OBUCHI used to be the chairman of the league.

Japan imposed a 914% tariff on imported konnyaku imo in 2005, and 1705% in 2008.

[Original Japanese]