Polysaccharide

Any sugar that can be hydrolyzed into a plurality of monosaccharide molecules or derivatives thereof is a polysaccharide. It is a macromolecular compound formed by the condensation and dehydration of twenty monosaccharides to tens of thousands of monosaccharide molecules. The polysaccharide may be formed by condensation of a monosaccharide, such as starch, cellulose or the like, to form a homopolysaccharide; it may also be formed by condensation of different monosaccharides or derivatives thereof, such as hemicellulose and the like. Plants, animals, and microorganisms in nature all contain polysaccharides. The polysaccharide may be present in a combined form with the protein in addition to being present in a free state. The commonality of plant polysaccharides is natural, health value and unique water-soluble colloidal properties, which can give food a higher nutritional value, a stable and palatable tissue structure, a refined appearance and a unique taste, and extend the shelf life. Natural plant polysaccharides are safer to the human body, with higher absorption and utilization. Water-soluble plant polysaccharides have excellent health care value, such as glucomannan in konjac, which is the soluble dietary fiber with the highest hydration viscosity found by humans, and has health functions such as satiety, hypolipidemic, hypoglycemic and laxative. Plant polysaccharides do not provide calories, but have a balanced nutrient effect on high-calorie, high-fat, high-protein dietary structures. For hydrophilic plant polysaccharides, people used to call it vegetable gum. Because of their hydrophilic colloidal properties, food production processing has thickeners, gels (formation) agents, film formers, emulsifiers and other food stabilizers. Effective development and utilization of plant polysaccharides will help improve human quality of life, improve human health, enrich human food resources, and create more economic value for the world's food industry. Starch is a polysaccharide stored in plants and is composed of two components, namely amylose and amylopectin. Among the starch granules, amylose is usually only 20 to 28%, and the rest is amylopectin. Amylose is composed of 250 to 300 G-glucose molecules linked by a 1,4 glycosidic bond in a linear form, curled into a helix, having a non-reducing end and a reducing end. The molecular weight of amylose varies widely, from thousands to even 150,000; it reacts blue with iodine because the inside of the helically curled amylose is occupied by molecular iodine (I2) when the amylose is suspended in water. . Amylopectin is a structure in which a short chain is formed by 24 to 30 D glucose molecules not only forming a short chain by α1,4 glycosidic bonds, but also a short chain linkage by α1,6 glycosidic bonds. The alpha-amylase of the animal's digestive tract (present in saliva and pancreatic juice) can optionally act on the α1,4 glycosidic bond to hydrolyze linear amylose to produce maltose and glucose. The beta amylase in plants acts on the non-reducing end of amylose to form maltose. Amylopectin can also be acted upon by alpha and beta amylases, but the alpha 1,4 glycosidic linkages and alpha 1,6 glycosidic linkages near the branching point are not themselves hydrolyzed by these enzymes. Under the combined action of alpha amylase and 1,6 glucosidase, amylopectin can be completely hydrolyzed to glucose and maltose. Agarose is an important component of agar, a unit formed by D-galactose and 3,6-anhydrogalactose, and is repeatedly condensed into a linear polysaccharide. Agarose can be dissolved in boiling water in a large amount, but when the temperature drops below 40 ° C, it becomes an insoluble gel. This agarose gel is also a kind of support commonly used in chromatography, but its formation is not the result of cross-linking but the hydrogen bond to crosslink the galactose chain, so it is unstable in an environment of too acid and alkali. .