Hydrolysis of lactose in acid whey using β‐galactosidase immobilized on porous glass particles: Preparation and characterization of a reusable catalyst for the production of low‐lactose dairy products

Abstract

Abstract Partially purified lactoses (β‐ D ‐galactoside galactohydrolase, EC 3.2.1.23) from Aspergillus niger , Ladobacillus helveticus , and Saccharomyces lactis were immobilized on diazotized porous glass particles (mean pore diameter, 86.5 nm: particle size diameters, 75–125 μm). In acid whey containing 4–4.5% lactose, A. niger lactase gave the highest activity (89 μmoles lactose hydrolyzed/g glass, min) at 55°C and pH 4.5. Glass‐immobilized A. niger laclases (lactase‐BG) retained much hydrolytic activity after storage and periodic use for 165 days at 55°C. For values of X greater than 30%, hydrolysis of 0.12 M lactose in acid whey by a continuous flow column packed with 2 ml of lactase‐BG particles could be correlated by X = 17.2( V / F ) + 12.5 where X = lactose hydrolysis, percent of lactose originally present; V = volume of packed bed of lactase‐BG, ml; F = flow rate of acid whey, ml/min.