Polysaccharides are polymeric carbohydrate structures, formed of repeating units (either mono- or di-saccharides) joined together by glycosidic bonds. Polysaccharides are characterized by the following chemical properties:  not sweet in taste, insoluble in water, do not form crystals when desiccated, compact and not osmotically active inside the cells,  can be extracted to form white powder, and general chemical formula of C_x(H₂O) _y.