
Polysaccharides are complex polymers containing only one monosaccharide, homopolysaccharides, or several different monosaccharides or monosaccharide derivatives, heteropolysaccharides. Many polysaccharides exist in the plant and animal kingdoms. However, only a few of these are known to be significant in mammalian nutrition, either as dietary constituents or as human cell metabolites.
The most common digestible polysaccharides in plants is starch, a polymer of glucose. Starch is present primarily in the cells of grains, fruits and tubers in the form of granules that, under microscopes examinations, appear to be typical for each starch. The composition of starches also differs somewhat, but all types contain both amylase, a straight chain polymer of glucoses, and amylopectin, a branch chain polymer. The average chain contains 20 to 25 glucose units with approximately 5 to 8 glucose molecules between branching points within the chain. On hydrolysis in the intestinal tract, starch yields dextrin and maltose and, eventually glucose.
Definitions for Polysaccharides