Konjac, also known as devil's tongue, is a perennial herbaceous plant belonging to the Araceae family, with 163 species worldwide, mainly distributed in Southeast Asia and Africa, while there are currently no records of cultivation in the Americas and Europe. China is the main producing country of konjac, with 21 varieties mainly distributed in Shaanxi, Hubei, Sichuan, Guizhou, Yunnan, and other regions. The further south from the main ridge of the Qinling Mountains, the more species are distributed. Konjac contains glucomannan, alkaloids, pectin, 17 essential amino acids, and 10 trace mineral elements, as well as rich dietary fiber. It is the only plant in the biological world that contains a large amount of glucomannan, which has preventive and therapeutic effects on "rich man's diseases" (such as hyperlipidemia, high cholesterol, diabetes, obesity, constipation, etc.), making it an ideal health food for middle-aged and elderly people, and it is favored in the global health food market.

       In Japan, konjac has become a must-have delicacy, known as "magic food." The uses of konjac are quite extensive; its powder can be used as a main ingredient to make various konjac foods or as an additive in other foods to improve their quality. In addition, konjac can also be used as a green, pollution-free raw material in cosmetics, textiles, construction, edible films, and emulsions.

60%

4.16%~7.86%

20%~30%

0.06%~0.54%

3.10%~4.70%

3%

Konjac Glucomannan (KGM) is a high-quality soluble hemicellulose and is considered the seventh nutrient fiber for the human body. Konjac Glucomannan has various unique physicochemical properties such as water solubility, water retention and thickening, stability, suspension, gelation, adhesion, and film formation, which give it extensive application and development value. Konjac Glucomannan is a new product obtained by processing and extracting from ordinary konjac flour. It further separates starch, pigments, and alkaloids from konjac flour, particularly removing harmful substances like sulfur dioxide found in ordinary konjac flour. It successfully overcomes the weaknesses of ordinary konjac flour, such as the presence of multiple pigments, alkaloids, and starch impurities, as well as the difficulty in swelling of branched fibers. In terms of water solubility, gel properties, and other physicochemical characteristics, it is significantly superior to ordinary konjac flour, especially in terms of product quality, which is good, has no special odor, and has a pleasing color, making it favored by a wide range of customers, serving as a substitute for ordinary konjac flour.

      Konjac glucomannan molecules contain a large number of hydrophilic groups such as hydroxyl and carbonyl groups, which can bind a significant amount of water. Through hydrogen bonds, molecular dipoles, induced dipoles, and instantaneous dipoles, they combine with water molecules to form large molecules that are difficult to move freely. In water, konjac glucomannan solutions become non-Newtonian fluids, and in gel foods, they promote the establishment of a network structure of konjac glucomannan macromolecules, with a water retention capacity of 40 times their own weight.

     Due to the high molecular weight of konjac glucomannan, its strong ability to bind water, and the high viscosity of its aqueous solution, a 1% konjac powder solution can reach a viscosity of several tens to hundreds of pascal-seconds, thus exhibiting excellent thickening properties. In addition, konjac glucomannan is non-ionic and compared to thickeners like xanthan gum and guar gum, its thickening ability is minimally affected by salt.

      The concentration of konjac glucomannan solution is between 2% and 4%. Under strong stirring, it undergoes shear thinning and has a certain fluidity. After standing, the fluidity decreases, gradually forming a gel. Konjac glucomannan has a strong gel synergistic effect when mixed with xanthan gum, carrageenan, and others; when compounded with carrageenan, the greater the proportion of konjac glucomannan, the stronger the gel toughness; conversely, the gel brittleness increases. The gels formed under the above conditions have thermal reversibility. However, when heated under alkaline conditions, such as in the presence of KOH, NaOH, Na2CO3, K2CO3, etc., the gels formed are thermally irreversible. This is due to the hydrolysis of the ester bonds formed by acetic acid and hydroxyl groups on the sugar residues in the konjac glucomannan chain when heated under alkaline conditions, which removes the acetyl groups, leaving the glucomannan in a bare state, and some intermolecular hydrogen bonds form, resulting in crystallization. This crystallization forms a network structure (i.e., gel), which exhibits thermal irreversibility.

      Konjac glucomannan has excellent film-forming properties after modification. Under alkaline conditions (pH>10), heating and dehydration can form a sticky, high transparency and density hard film, which is stable in cold and hot water as well as acidic solutions. Adding moisturizers can change the mechanical properties of the film. As the amount of moisturizer increases, the strength of the film decreases while its flexibility increases. The water permeability of the film is influenced by the nature of the additives; adding hydrophilic substances increases the water permeability of the film, while adding hydrophobic substances decreases it.

      Most substances are solid at low temperatures and liquid at high temperatures. However, konjac glucomannan gel has a peculiar reversibility; it is liquid or paste-like at low temperatures (10-15℃), while it becomes solid or semi-solid at room temperature or when heated above 60℃, returning to a liquid state upon cooling. This unique property makes konjac glucomannan actively useful in food processing and the preservation of agricultural products. In addition, konjac glucomannan also has emulsifying, suspending, and stabilizing properties. These properties are closely related to the pH of the system. When pH<10, it mainly exhibits water retention, thickening, emulsifying, suspending, and stabilizing effects; when 10<pH<12, it shows reversibility of gel and sol at different temperatures, demonstrating film formation, shaping, and preservation effects; when pH>12, it forms thermally irreversible gel under heating conditions, exhibiting film-forming properties.