#Properties#
Properties of konjac
Konjac, Amorphophallus Konjac K. Koch is a tuberous plant native to southern China whose scientific name comes from the resemblance of its floral appendage to animal genitals. Konjac belongs to the Araceae family and grows naturally in Japan, Vietnam, South Korea and Indonesia. Its name is mentioned in ancient Chinese texts dating back over 2000 years ago.
Widely cultivated as a food plant, konjac was consumed during famines by various tribes after obtaining a starch from it. The gel prepared from its flour has long been used in traditional Chinese medicine to reduce intestinal disorders, fight against tumors, and treat burns. Konjac was also recommended in the treatment of asthma, cough, hernias, breast pain as well as hematological and skin disorders[1].
The flour extracted from the rhizomes of Amorphophallus Konjac K. Koch is used in Far Eastern cuisine to make noodles, tofu and snacks. The pasty jelly made from konjac is popularised under the Japanese name konnyakua. The underground part of the plant contains a soluble fiber with slimming properties. These benefits of konjac mean that it is offered on the market as a slimming treatment in the form of natural food supplements.
Recently, purified konjac flour, called konjac glucomannan, was introduced in the United States and Europe as a food additive or supplement in the form of capsules or a drink mix. Indeed, the leaves of the plant contain a lot of mannan, an alkaloid and a little starch; the petiole and the peduncle contain mannose[2], dextrose and levulose. The konjac rhizome is rich in mannan made up of sticky and cellulosimorphic polyanhydrides forming mannose sugar[3].
The health benefits of Amorphophallus Konjac K. Koch mostly relate to glucommanan, a viscous dietary fiber extracted from the root of the plant[4]. A hydrocolloidal polysaccharide, glucommanan is an active ingredient that swells on contact with water and thus serves as an appetite suppressant. This specific property of konjac has earned it recognition by the authorities as an effective plant for lowering cholesterol levels and especially weight loss. Indeed, glucomannan contributes to the maintenance of normal cholesterol levels and promotes the success of low-calorie diets. By swelling the digestive tract, viscous dietary fibers create a feeling of satiety.
Research reveals that glucomannan is an effective ingredient for significantly decreasing weight in overweight or obese people. By slowing the body's absorption of sugar from the diet, this low calorie fiber also promotes good blood sugar levels andimproves metabolic responses to insulin[5] Konjac glucomannan supplements are beneficial for better gut health. These active ingredients make the stools softer and fight against constipation[6]. The properties of konjac thus prevent certain chronic diseases thanks to the regulation of the metabolism: hypocholesterolemic action and hypoglycemic activity.
Also, a diet containing konjac flour is considered healthier, and these foods are popular in many Asian and European markets.
[1] Chua M, Baldwin TC, Hocking TJ, Chan K. Traditional uses and potential health benefits of Amorphophallus konjac K. Koch ex N.E.Br. J Ethnopharmacol. 2010 Mar 24;128(2):268-78. doi: 10.1016/j.jep.2010.01.021. Epub 2010 Jan 15. PMID: 20079822. https://doi.org/10.1016/j.jep.2010.01.021
[2] Wang P, Zheng Y, Li Y, Shen J, Dan M, Wang D. Recent advances in biotransformation, extraction and green production of D-mannose. Curr Res Food Sci. 2021 Dec 16;5:49-56. doi: 10.1016/j.crfs.2021.12.002. PMID: 35005631; PMCID: PMC8718577.
[3] Behera, S. S. & Ray, R. C. (2016). Konjac glucomannan, a promising polysaccharide of Amorphophallus konjac K. Koch in health care. International Journal of Biological Macromolecules, 92, 942–956. doi:10.1016/j.ijbiomac.2016.07.098. Retrieved from https://pubmed.ncbi.nlm.nih.gov/27481345/
[4] Devaraj RD, Reddy CK, Xu B. Health-promoting effects of konjac glucomannan and its practical applications: A critical review. Int J Biol Macromol. 2019 Apr 1;126:273-281. doi: 10.1016/j.ijbiomac.2018.12.203. Epub 2018 Dec 23. PMID: 30586587.
[5] Sood N, Baker WL, Coleman CI. Effect of glucomannan on plasma lipid and glucose concentrations, body weight, and blood pressure: systematic review and meta-analysis. Am J Clin Nutr. 2008 Oct. 88(4):1167-75.
[6] Chen, H. L., Cheng, H. C., Liu, Y. J., Liu, S. Y., & Wu, W. T. (2006). Konjac acts as a natural laxative by increasing stool bulk and improving colonic ecology in healthy adults. Nutrition, 22(11-12), 1112–1119. doi:10.1016/j.nut.2006.08.009. Retrieved from https://pubmed.ncbi.nlm.nih.gov/17027233/
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