Hydrolysis of D ‐galactosides in an open tubular lactase reactor

Lactose (β‐galactosidase) was attached to the inner surface of nylon tubing. Tubes of various lengths were used to bring about the hydrolysis of o ‐nitrophenyl‐β‐ D ‐galactoside and of lactose in skim milk. The results with the former substrate were analyzed in the light of a theoretical treatment of Kobayashi and Laidler ( Biotechnol. Bioeng. , 16 , 99, 1974), with the conclusion that the reaction is intermediate between diffusion‐free and completely diffusion‐controlled behavior. The results with skim milk show that with a single 46 m tube and continuous circulation, 90% of the lactose is removed within 20 hr. A battery of ten such tubes, with single passage, at a flow rate of 2 cm/sec, would remove more than 99% of the lactose in less than 40 min.