Konjac was first put in the list of medicinal plants in Shen Nong’s Herbal Classic written more than 2000 years ago in China, and records were made of its curing and health-promoting functions in many classic works of Chinese medicine written in the Dynasties of Later Liang, Song, Ming and Qing. In his famous works Compendium of Material Medica, Li Shizhen records, “Konjac is cold in property and pungent in flavor. Used as a medicine, its tuber has the functions of detoxification, subsiding swelling, liquefying the phlegm and soothing asthma.” In Chinese traditional medicine, konjac has been used to treat cough, hernia, breast pain, burn and others. It is believed that when boiled for enough time, konjac helps to improve the function of the stomach and promote digestion. It is recorded in another Chinese classic that konjac can “remove mud and sand from the belly and is especially helpful to the male”, though the author himself did not understand exactly why. It mentioned that konjac could be used to treat tuberculosis but patients of other diseases should avoid taking too much of it.
Seen from the perspective of nutriology, konjac is a food low in calories, protein and vitamins and high in dietary fiber. It is the dietary fiber that constitutes its effective nutritional component. Konjac fine flour is obtained by processing the corm of konjac with physical procedures and represents the concentrated product of its effective nutritional component. Glucomannan, a soluble semi-cellulose, is the major active ingredient of konjac fine flour. The nutritional and healthful functions of konjac consist in the regulation of nutrition imbalance by dietary fiber. Its health-promoting functions are as follows:
A. prevention and treatment of constipation;
B. regulation of lipid metabolism;
C. improvement of sugar metabolism;
While konjac finds wide application in various fields, its main fields of applications are food, medicine and industry as well as the comprehensive exploitation of its flying powder. From the perspectives of nutrition, health and medicine, konjac is used in the following three aspects:
1． As the primary raw material or additive in food industry: As the science and technology related to konjac develop and people get a better understanding of the plant, konac fine flour is increasingly employed as an important raw material or additive in the production of various foods, drinks, jelly and juice.
2． As healthful foods: Various specific healthful foods can be developed for the consumption by specific groups of people.
3． Uses in pharmaceutical industry: For the treatment of constipation there are already available in
The primary component of economic significance of konjac is konjac glucomannan (KGM). KGM is a high molecular polysaccharide and is formed when the residues of glucose and mannose with a molecular ratio of 1:1.6～1.7 are bound together by β-1,4 glycoside. Glucomannan falls into the category of semi-cellulose and represents the most healthful of the group of cellulose which is considered to be the seventh essential nutritional substance for human body. When the insoluble cellulose contained in common fruits or vegetables is taken in by human body, it may be excreted out of the body in its original shape. When it comes to KGM, it is a quite different story. According to the research by some scientists of the West China University of Medicine, under the glycolysis by the bacteria in the intestinal tract, KGM produces hydrogen, carbon dioxide, methane, water and short-bond fatty acids, which combine with bile acid in the intestine through ion exchange and thus increase the amount of cholesterol used for the synthesis of bile acid. As a result, cholesterol level in the blood is lowered. KGM was also found to help reduce the chance of the formation of gall stone while bile is released from the bile tract. It also reduced the formation of carcinogenic substances from the products of bile acid metabolism and helped them to be excreted from the body, thus helping reduce the chance of colon cancer. Konjac can significantly lower the level triglyceride in the blood, and blood fat level will not continue lowering once the normal level is reached. So konjac helps to regulate lipid metabolism and decrease the incidence rate of atherosclerosis and coronary heart disease. KGM, as a dietary fiber, cannot be digested and absorbed, contain no calories, gives a feeling of stomach fullness and reduces or retards glucose intake and, therefore, is a desirable supplementary medicine for the treatment of diabetes. It can be used to prevent obesity or to help lose weight gradually. KGM, as a soluble cellulose, can absorb and keep a great amount of water, and thus can increase the volume of feces and makes it softer, which will help excretion and prevent constipation.Owing to its various particular physico-chemical properties of water solubility, water-holding, thickening, suspending, jelling, adhesive and film-forming, KGM finds wide application and has a promising prospect for development.