Lactose, a milk sugar, is the carbohydrate normally obtained from whey and is the most abundant of the milk solids by weight. Lactose is a disaccharide composed of the monosaccharides Alpha-D-glucose and Beta-D-galactose. It is a reducing sugar that can, in some circumstances, react freely with amino acid groups in proteins. Lactose is a versatile ingredient that provides end-users with many functional benefits in finished products. The United States manufactures food grade, pharmaceutical grade and industrial grade lactose products, each with its own set of specifications.