Lactose hydrolysis by β-galactosidase enzyme: optimization using response surface methodology

• This paper demonstrates the comparative results of Lactose hydrolysis using β-galactosidase enzyme in free and immobilized mode .
• In this paper the enzyme has been immobilized in calcium alginate beads.
• In this paper Response Surface Methodology (RSM) was used to optimize the parameters affecting lactose hydrolysis both in free mode and immobilized mode.
• The results obtained will be useful in hydrolysis of important biomolecule, lactose present in dairy effluent to fermentable sugars for further use.

In the present study, it was aimed to optimize the process of lactose hydrolysis using free and immobilized β-galactosidase to produce glucose and galactose. Response surface methodology (RSM) by central composite design (CCD) was employed to optimize the degree of hydrolysis by varying three parameters, temperature (15–45 °C), solution pH (5–9) and β-galactosidase enzyme concentration (2–8 mg/mL) for free mode of analysis and sodium alginate concentration (2–4%), calcium chloride concentration (3–6%) and enzyme concentration (2–8 mg/mL) for immobilized process. Based on plots and variance analysis, the optimum operational conditions for maximizing lactose hydrolysis were found to be temperature (35.5 °C), pH (6.7) and enzyme concentration (6.7 mg/mL) in free mode and sodium alginate concentration (3%), calcium chloride concentration (5.9%) and enzyme concentration (5.2 mg/mL) in immobilized mode.