Acid-Catalyzed Hydrolysis of Lactose in Whey and Aqueous Solutions

Lactose in fresh cottage cheese whey and aqueous solutions was successfully hydrolyzed in .5, 1, 2, and 3 Normal hydrochloric acid at 50, 60 and 70 C. First-order rate constants and half-times were calculated from glucose released by hydrolysis. Rates in both whey and aqueous lactose solutions were comparable at 50 and 60 C whereas at 70 C whey lactose rates appeared consistently lower than aqueous lactose rates (by approximately 10 to 20%). This was attributed to loss of free glucose through the browning reaction. Undesirable side reactions were minimized by conducting the hydrolyses at temperatures well below 100 C. The data demonstrate the feasibility of using mineral acid for whey lactose hydrolysis.