Enzymatic clarification of fruit juices using xylanase immobilized on 1,3,5-triazine-functionalized silica-encapsulated magnetic nanoparticles

Abstract

1,3,5-Triazine-functionalized silica encapsulated magnetic nanoparticles (MNPs) have been successfully synthesized. The morphology, structure and properties of functionalized nanoparticles were investigated through different analytical tools including Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray powder diffraction. Due to the magnetic nature and the presence of triazine functionalized groups, the as-prepared Fe3O4@SiO2 nanoparticles were employed as magnetic carriers for xylanase immobilization. The xylanase immobilized on functionalized MNPs (Xy-MNP) exhibited excellent catalytic activity at pH 6.5 and 65°C. Notably, Xy-MNPs had significant effect on juice clarity and showed quite impressive stability, even after 10 reaction cycles in the enrichment of the juices clarification, it could still retain about 55% of the initial activity. The Xy-MNPs illustrated similar clarity enrichment for three types of fruit juices, after 5h incubation at 50°C. The effect of metal ions and organic solvents on the activity of immobilized xylanase was investigated. The results showed an increasing in the catalytic activity of Xy-MNPs in the presence of some metal ions while they have inhibitory effect on the activity of free xylanase. Also both free and immobilized xylanase were inhibited in the presence of 50% (v/v) organic solvents, whereas the Xy-MNPs activity was significantly increased in the presence of 10% (v/v) organic solvents. It is hoped that the 1,3,5-triazine-functionalized Fe3O4@SiO2 nanoparticles may find an application in modern biotechnology.