Stability of β-D-galactosidase immobilized in polysaccharide-based hydrogels

The stability of beta-D-galactosidase immobilized in Arabic gum-based and chitosan-based hydrogels was studied during standard lactose hydrolysis reactions. Such studies were conducted considering freeze-drying and air drying methods of the hydrogels, beta-D-galactosidase immobilization capacities, pH values and temperatures of the aqueous enzyme solutions. The freeze-dried hydrogel was more suitable for beta-D-galactosidase immobilization than the air-dried hydrogel. It was associated with the exposure of active sites in the porous hydrogel network. Higher beta-D-galactosidase immobilization capacity was found using the chitosan-based hydrogel compared to the Arabic gum-based hydrogel. beta-D-galactosidase immobilized in both hydrogels was submitted to five consecutive cycles of lactose hydrolysis. beta-D-galactosidase activities in the hydrogels increased with the increase in pH and temperature. The exception was the hydrolysis reactions at 50.0 +/- 1.0 degrees C, during which both the free and immobilized beta-D-galactosidase exhibited minimal enzymatic activities, likely due to denaturation. Overall, the reaction temperatures for the free and immobilized beta-D-galactosidase could be fixed at either 37.0 or 25.0 +/- 1.0 degrees C. beta-D-galactosidase immobilized in Arabic gum-based and chitosan-based hydrogels was more stable in acidic media than the free beta-D-galactosidase. It is an excellent advantage for the application of beta-D-galactosidase immobilized in both hydrogels.

Automated summary

The stability of beta-D-galactosidase immobilized in Arabic gum-based and chitosan-based hydrogels during lactose hydrolysis reactions was investigated. The freeze-dried hydrogel was more suitable for enzyme immobilization, with chitosan-based hydrogel showing higher immobilization capacity. The immobilized enzyme in both hydrogels exhibited better stability in acidic media compared to the free enzyme, an advantage for their application.