Oligosaccharides are low-molecular-weight polysaccharides, during hydrolysis of which from 2 to 10 monosaccharide molecules are formed.When the alcohol component of a glycoside is provided by a hydroxyl function on another monosaccharide, the compound is called a disaccharide.The most important are disaccharides, that is, saccharides containing two monosaccharide residues.These include sucrose, maltose, lactose and cellobiose.When they are hydrolyzed, two monosaccharides are formed.