Lactose is a disaccharide of galactose plus glucose. Corn syrup contains glucose, fructose (monosaccharides), and maltose (disaccharide). Maltitol is a disaccharide produced by hydrogenation of maltose obtained from starch. It is a disaccharide, a molecule composed of two monosaccharides&colon; glucose and fructose. A disaccharide is formed when a dehydration reaction joins two monosaccharides. A disaccharide is formed from two monosaccharides. Two joined monosaccharides are called a disaccharide and these are the simplest polysaccharides. Maltose, another common disaccharide, is condensed from two glucose molecules. Keratan sulfate, also called keratosulfate, is formed from repeating disaccharide galactose units and N-acetylglucosamines. Both consist of a variably sulfated repeating disaccharide unit. Sucrose is a disaccharide made up of glucose and fructose. Sucrose which is disaccharide is usually used as a sweetening agent. Sucrose gives a positive test as it is a disaccharide consisting of fructose and glucose. It is a disaccharide that consists of one glucose and fructose molecule. The best-known disaccharide is sucrose (table sugar).