Amorphophallus konjac

Amorphophallus konjac, commonly known as moyu (, lit. 'demonic taro', 'magical taro'), juruo (), konnyaku, or konjac is a species of flowering plant in the family Araceae. In English, it is also referred to as devil's tongue, a term that also refers to the plant itself, and as konnyaku in Japanese. It can be made into white or black cake, as well as a kind of noodle called shirataki.

Moyu was first domesticated in Southwest China about 2000 years ago, where Yi people and other early cultivators developed methods to detoxify the naturally irritating corm through repeated boiling and the use of alkaline ash water. These techniques enabled the plant to transition from a toxic wild tuber to a fiber-rich food source, and they form the basis of the traditional processing methods still used in parts of China today.

Description

It is a perennial plant, growing from a large corm up to 25 cm (10 in) in diameter. The single leaf is up to 1.3 m (4 ft) across, bipinnate, and divided into numerous leaflets. The flowers are produced on a spathe enclosed by a dark purple spadix up to 55 cm (22 in) long.

It is a relative of the titan arum (A. titanum), one of the largest flowering plants in the world and a congener of moyu.

All parts of the moyu plant are toxic, with the corm being the most poisonous. It cannot be eaten raw and must be processed before consumption. Poisoning can cause burning, itching pain, and swelling of the tongue and throat if digested.

Distribution and habitat

Wild forms grow naturally in China (Yunnan in the southwest) and Southeast Asia.

Uses

thumb|upright|Amorphophallus konjac in bloom

thumb|upright|Amorphophallus konjac male (top) and female (bottom) flowers

thumb|Japanese konjac gel, with [[hijiki seaweed mixed in]]

thumb|Konjac corm used for preparing food

thumb|[[Sashimi konnyaku, usually served with a miso-based dipping sauce rather than soy sauce]]

Moyu (konjac) is grown in warm subtropical to tropical areas of East and Southeast Asia, from China and Japan south to Indonesia and Vietnam (USDA hardiness zone 6–11). and it is prized for its large starchy corms, used to create a flour and jelly of the same name. It is also used as a vegan substitute for gelatin.

China

Native to China, moyu has been used for more 2000 years. Early medicinal references to the plant appear in Shennong Bencaojing (Chinese: 神农本草经, lit. 'Shen-nong's Herbal Classics'), a foundational herbal materia medica traditionally associated with the Western Han dynasty (206 BC – 8 AD), describing the corm as a medicinal substance valued for its detoxifying and expectorant properties. It is valued more for its texture than flavor. is a Japanese food consisting of konjac cut into noodle-like strips. It is usually sold in plastic bags with accompanying water, which is drained before cooking. The name literally means 'thread-konjac'.

Japanese konnyaku is made by mixing konjac flour with water and limewater. Konjac cannot be eaten raw because it contains oxalic acid. The product comes in various shades of gray; konnyaku made from corm are naturally dark, while those made from konjac flour are white. Japanese documents from around the 18th century mentions its intestinal cleansing property.

Traditional medicine

The dried corm of the konjac plant contains around 40% glucomannan gum. This polysaccharide makes konjac jelly, a viscous substance that may be used in traditional Chinese medicine.

Fruit jelly

Konjac can also be made into a popular East Asian fruit jelly snack, known variously in the US as lychee cups (after a typical flavor) or konjac candy, usually served in bite-sized plastic cups. This fruit jelly was first sold in Japan in 1979.

Choking risk

Perhaps because of several highly publicized deaths and near-deaths in the San Francisco Bay Area among children and elderly people caused by suffocation while eating konjac candy, the US Food and Drug Administration (FDA) issued product warnings in 2001, and there were subsequent recalls in the US and Canada. Choking and intestinal blockage risk warnings have been published at more recent websites.

Unlike gelatine and some other commonly used gelling agents, konjac fruit jelly does not melt readily in the mouth. Some products form a gel strong enough to require chewing to disintegrate the gel. Though the product is intended to be eaten by gently squeezing the container, a consumer can suck the product out with enough force to unintentionally lodge it in the trachea. Because of this hazard, the European Union and Australia banned konjac fruit jelly.

Some konjac jelly snacks are not of a size and consistency that pose a choking risk, but are nonetheless affected by the government bans. Some products that remain in East Asian markets have an increased size, unusual shape, and more delicate consistency than the round, plug-like gels that were associated with the choking incidents. The snacks usually have warning labels advising parents to make sure their children chew the jelly thoroughly before swallowing.

In 2008, Japan's largest manufacturer of konjac snacks, MannanLife, temporarily stopped producing the jellies after a 21-month-old Japanese boy choked to death on a frozen MannanLife konjac jelly. 17 people died from choking on konjac between 1995 and 2008. MannanLife konjac jelly's packaging added a note to consumers, advising them to cut the product into smaller pieces before serving it to small children. To prevent such accidents, they developed and began selling drinkable konjac jelly in 2005.

In 1999, 8-year-old Michelle Enrile from San Jose, California, choked on a piece of konjac gel candy. She lapsed into a coma and died 27 months later at age 11. The Enriles won a $16.7 million judgment against the Taiwanese manufacturer of the candy.

Vegan seafood alternative

Konjac corm powder has a noticeably fishy smell and is used as an ingredient in vegan alternative seafood products. It can be incorporated into plant-based versions of seafood. For Chinese cooking, thin strands of konjac gel can be used as substitute for shark fins when preparing a plant-based version of shark fin soup.

Other uses

thumb|A konjac sponge for facial cleansing

Konjac can also be used for facial massage accessories, which are popular in Korea and gaining popularity in the West. Most commonly this is through the use of a konjac sponge, which is unique in that it can be used on sensitive skin that may become easily irritated with more common exfoliating tools (such as loofahs or washcloths).

It can be used in the formulation of drugs and devices such as oral colon-targeting drug delivery systems (OCDDS), which enable drugs to be delivered directly to the colon.

In traditional hand papermaking in Japan, konnyaku imparts strength to paper for dyeing, rubbing, folding—and other manipulations, such as momigami.

Shirataki noodles have gained popularity in the US for their low carbohydrate content.

Notes

References