Hydrolysis of lactose using β-D-galactosidase immobilized in pectin-based hydrogels: Modeling and optimization by factorial design

Abstract

In this work, we studied the hydrolysis of lactose using β-d-galactosidase immobilized in pectin-based hydrogels and optimized the process using a central composite rotatable design and response surface methodology. The experimental conditions were established by optimizing the enzyme immobilization capacity of the hydrogels and glucose concentrations formed during the hydrolysis of lactose using the immobilized enzyme (dependent variables). Optimal temperature, initial enzyme concentration, and pH (independent variables) for immobilization in the hydrogel without pine fiber were 44.0 ± 1.0 °C, 7.0%, and 6.4, respectively. These values were approximately 35.0 ± 1.0 °C, 6.3%, and 5.6 for both composite hydrogels containing 5 and 10% pine fiber. The immobilization of β-d-galactosidase at optimum pH led to the absence of hydrolytic activity owing to enzyme overload, whereas higher glucose concentrations were found during the hydrolysis of lactose when β-d-galactosidase was immobilized at pH 4.0. Thus, the immobilization protocols led to β-d-galactosidase immobilized in the hydrogels with high catalytic capacity. In conclusion, the hydrolysis of lactose can be performed using β-d-galactosidase immobilized in pectin-based hydrogels for the production of low-lactose foods.