Konjac, a traditional agricultural food with a history of 1500 years in both China and Japan. It is the tuber (root) of the perennial plant of Amorphophallus konjac.

Moisture

Moisture has a great influence on the quality of dried konjac flour. Fresh konjac tubers have a high water content (80%-85%), so it is easily moldy, spoiled and cannot be stored for a long time.

Therefore, in order to prolong shelf life, the konjac is usually processed into dried slices or chips to reduce the water content (generally about 15%) after harvest. 

SO2

Konjac slices/chips are prone to browning during processing, so SO2 is often added to prevent browning and to make a bleaching effect.

That’s why you will see the item of SO2 content in the specification of both konjac gum and konjac glucomannan.

The dried konjac needs to be further processed into konjac flour to be used as food raw materials. The quality of the konjac flour primarily depends on the source of the konjac plant.

Components

The glucomannan is the main component in konjac tuber in a dry basis, the assay of which is about 30%-50%, and varies according to the types of konjac, and the rest are cellulose, starch, protein, soluble sugars, inorganic salts, alkaloids, vitamins and etc.

http://www.chinafooding.com/Konjac_Gum