Lactose

The main sugar present in milk called also sugar of milk or milk sugar When isolated pure it is obtained crystalline it is separable from the whey by evaporation and crystallization It is a disaccharide with the formula C12H22O11 being chemically 4 beta D galactosido D glucose It has a slightly sweet taste is dextrorotary and is much less soluble in water than either cane sugar or glucose Formerly called lactin When hydrolyzed it yields glucose and galactose In cells it may be hydrolyzed by the enzyme beta galactosidase