What is konjac made from?
It is actually made from a certain kind of yam. Let me explain in 30 seconds.Konjac is made from the konjac yam, a plant in the same family as taro. The yam is dried and ground into powder, mixed with water and kneaded, and then an alkaline coagulant is added to make it set. What makes it set is a substance in the yam called glucomannan. Finished konjac is more than 95% water.
Made from a relative of taro
According to materials from Japan's Ministry of Agriculture, Forestry and Fisheries, the konjac yam belongs to the genus Amorphophallus in the arum family, the same family as taro, and is said to come from Southeast Asia. Konjac is made from its ball-shaped underground stem (called a corm), which grows large in the soil over 2–3 years. It has been grown in Japan since long ago.
Glucomannan makes it set
What makes konjac set is a substance in the yam called glucomannan. According to research materials from Gunma University, glucomannan is a polysaccharide made of many sugars, glucose and mannose, linked together, and it is the main component of konjac. Materials from JETRO (the Japan External Trade Organization) explain that most konjac yams in Southeast Asia contain no glucomannan, so they do not set even when processed.
Kneading the powder and setting it
Most konjac is made from seiko, a powder made by drying and grinding the yam. At factories, the seiko is mixed with water to a strength of about 3% and kneaded. When an alkaline coagulant such as calcium hydroxide is added, it turns into a gel (a wobbly, jelly-like mass). It is shaped in a mold, boiled, and soaked in water to remove its harsh taste (called aku-nuki). Then it is ready.
Alkali brings the molecules together
Gunma University's research materials confirm that when alkali is added and the mixture is heated, small parts of glucomannan called acetyl groups come off, and the molecules gather together and set. Konjac made this way contains more than 95% water. That is why a small amount of ingredients can make a lot of konjac.
Want to know more?
- There is also nama-imo konjac, made directly from fresh yams that are grated instead of ground into powder, with a coagulant added.
- Gunma Prefecture grows more than 90% of Japan's konjac yam harvest, and the crop is important for supporting communities in the mountains.
- Konjac yams are grown by digging up the small yams called kigo that form in autumn and planting them again the next spring, over and over.
Quick quiz: test yourself
What is konjac made from?
Show the answer
- Seaweed
- Soybeans
- Konjac potatoes
Konjac potatoes Konjac potatoes, relatives of taro, are dried and ground into powder, mixed with water, and set into a jelly by adding an alkaline firming agent.
Konjac potatoes, relatives of taro, are dried and ground into powder, mixed with water, and set into a jelly by adding an alkaline firming agent.
Next quiz ›Sources
- こんにゃくをめぐる事情（令和8年7月）農林水産省 (in Japanese)
- こんにゃく製品ができるまで埼玉県 農林部 生産振興課 (in Japanese)
- 冷凍・解凍プロセスにおけるこんにゃく物性の制御（事業成果報告会資料）群馬大学 食健康科学教育研究センター (in Japanese)
- こんにゃく｜日本産食材ピックアップ日本貿易振興機構（ジェトロ） (in Japanese)
This article was written after checking the sources above as of 2026-10-03. Explanations may change as research progresses. Photo credits are shown below each photo.
