Immobilization of β-glucosidase onto silicon oxide nanoparticles and augment of phenolics in sugarcane juice

Purified beta-glucosidase was immobilized on SiO2 nanoparticles with 52 % efficiency and 14.1 % yield. It had a temperature optima at 60 degrees C and pH optima of 5.0. Immobilized enzyme was fairly stable at 60-70 degrees C. After immobilization, the K-m value of beta-glucosidase for p-nitrophenyl-beta-D-glucopyranoside (pNPG) increased from 0.9 to 1.074 mM and V-max decreased from 3.5 to 1.513 U/mg. The immobilized enzyme showed improved storage stability at temperature 4 and 25 degrees C and was reusable for up to ten cycles with 70 % residual activity in pNPG and 60 % residual activity in sugarcane juice treatment. Sugarcane juice density, viscosity; surface tension etc. changed after treatment with immobilized beta-glucosidase. beta-Glucosidase treated sugarcane juice showed higher phenolics than untreated sugarcane juice. Caffeic acid which was absent in juice, was detected in beta-glucosidase treated juice at a concentration of about 1 mg/L.