Freezing point measurement of lactose hydrolysis in acid whey and lactose solutions

A method for determining lactose hydrolysis by freezing point determinations is described. There is a direct relationship between freezing point and lactose hydrolysis in neutralized acid whey (r = 0.985) and lactose solutions (r = 0.998). In both the acid whey and the lactose solutions that contained 4.6 to 5.0% lactose, the freezing point was depressed approximately 0.050 degrees H for each 1% lactose hydrolyzed.