Abstract: Bad solubility, low saccharinity of lactose and lactose intolerance have caused low availability of whey. Nowβ-galactosidase was applied for hydrolysis of lactose in whey. The treated lactose in whey improved saccharinity and solubility thus easily utilized. Papers studied the effects of initial lactose concentrations and enzyme dosage, temperature and pH on degree of lactose hydrolysis. Orthogonal test was designed to identify optimum hydrolysis conditions for yielding most monomeric saccharides. The optimum conditions of hydrolysis for lactase was that substrate concentration 15%, 40 ℃, 3 h and of lactase dosage 90 U/g. Under these conditions the hydrolysis degree is 68%.

Key words: whey, lactose, hydrolyze, lactase