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It is a general name for konjac powder, which can refer to both konjac gum and konjac glucomannan. Both konjac gum and konjac glucomannan (KGM) are derived from konjac flour.

Types of konjac flour
Konjac flour is made from the grinding of slices/chips of dried konjac. According to the purification of glucomannan, it can be classified into three types: common konjac flour, konjac gum and konjac glucomannan.

The color of konjac flour is an important item for judging the quality of konjac flour. The more white the color, the more the content of glucomannan in it.

1. Common konjac flour
Here means unpurified konjac flour and with the following properties:

Smell: with the inherent smell of konjac and a slight smell of sulfur dioxide.
Appearance: white, with a small amount of yellow, brown or black particles.
Purity: a very simple purification process to remove starch and cellulose.
Glucomannan content: not less than 65%.
Viscosity: ≥ 14,000 mpa.s
Mesh size: commonly with 40-120mesh and above 120mesh in the market.
2. Konjac gum
Also known as purified konjac flour, obtained by aqueous extraction of konjac flour. It is not claimed as dietary fiber and so without physiological benefits.

Smell: with the inherent smell of konjac.
Appearance: white to cream to light tan powder.
Glucomannan content: not less than 75%.
Viscosity: ≥ 23,000 mpa.s.
3. Konjac Glucomannan
Konjac glucomannan (KGM) is a natural food gum extracted from the hemicellulose component in the cell walls of Amorphophallus konjac. It is also a water-soluble dietary fiber.

KGM is a natural high-molecular-weight polysaccharide, with excellent hydrophilicity, gelability, emulsification, film-forming and thickening effect.

Due to these properties, KGM has a wide range of applications in food.

Manufacturing process

Glucomannan is produced by washing konjac flour with water-containing ethanol as it is easy to absorb water and insoluble in ethanol.

The ethanol precipitation manufacturing process is to isolate glucomannan by removing starches, cellulose, protein and other components. And follows centrifugation, milled, drying and other processes to obtain pure KGM.

Structure

Glucomannan is composed of D-mannose and D-glucose units at a molar ratio of 1.6:1.0, connected by b(1-4)-glycosidic bonds.