Application of immobilized enzymes to accelerate the conversion of genistin to genistein in pigeon pea root extracts and the evaluation their antioxidant activity

The effect of incubation of pigeon pea root extracts with immobilized β-glucosidase on the conversion of genistin to genistein was investigated. β-Glucosidase was effectively immobilized on alginate by the method of crosslinking–entrapment. After optimization, the incubation conditions were as follow, amounts of immobilized β-glucosidase 30 U, temperature 30 °C, pH = 4 and incubation time 2 h. On the optimal conditions, about 94.9% of genistin was conversed to genistein, and the content of genistein was 0.689 mg/mL, which increased 63.7% after incubation. Immobilized β-glucosidase possessed extended stability and higher reusability. Furthermore, the antioxidant activity of genistein, genistin and the extracts with and without incubation were assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay. The IC50 value of extracts after incubation with immobilized β-glucosidase reached 726.21 ± 11.25 μg/mL, which was higher than that of the extract (932.76 ± 13.75 μg/mL) without incubation.

► The immobilization method facilitates the efficient recovery and reusability of β-glucosidase.
► The immobilization enhanced stability of enzyme, under both storage and operational conditions.
► Under the optimal incubation conditions about 94.9% of genistin was conversed to genistein.