Structural description

Glucomannan is a dietary fiber obtained from tubers of Amorphophallus konjac cultivated in Asia. Flour from the konjac tubers is used to make Japanese shirataki noodles which are very low in calories. The polysaccharide consists of glucose (G) and mannose (M) in a proportion of 5:8 joined by β(1-4) linkages. The basic polymeric repeating unit has the pattern: GGMMGMMMMMGGM. Short side chains of 11-16 monosaccharides occur at intervals of 50-60 units of the main chain attached by β(1-3) linkages. Also, acetate groups on carbon 6 occur at every 9-19 units of the main chain. Hydrolysis of the acetate groups favors the formation of intermolecular hydrogen bonds that are responsible for the gelling action.

Possible biomass sources

Glucomannan comprises 40% by dry weight of the roots or corm of the konjac plant. It is also a hemicellulose that is present in large amounts in the wood of conifers and in smaller amounts in the wood of dicotyledons.

Activities and Uses

As a food additive, glucomannan is used as an emulsifier and thickener. It has E number E425(ii). Glucomannan is used as a hunger suppressant because it produces a feeling of fullness by creating very viscous solutions that retard absorption of the nutrients in food. One gram of this soluble polysaccharide can absorb up to 200 ml of water, so it is also used for absorbent articles such as disposable diapers and sanitary napkins. Glucomannan also makes up the majority of shirataki noodles.

Glucomannans show health benefits for: constipation, cholesterol, diabetes, obesity (An et al., 2010. Carbohydrate Polymers).


Glucomannan oligosaccharides (cut off < 10 kDa) - 10 mg

Glucomannan oligosaccharides (cut off < 10 kDa) - 10 mg

Oligomers obtained from glucomannan polysaccharide hydrolysis and purified by 10kDa cut-off ultrafiltration.