Production of d-tagatose in packed bed reactor containing an immobilized l-arabinose isomerase on alginate support

Abstract

In this study, l-arabinose isomerase (L-AI, E.C. 5.3.1.4) was immobilized on alginate beads and packed in a reactor for continuous synthesis of d-tagatose from d-galactose of whey. The developed L-AI entrapped on alginate bead ([email protected]) was characterized by scanning electron microscopy, confocal laser scanning microscopy, fourier transform infrared spectroscopy and thermogravimetric analyzer. The effect of pH and temperature on free L-AI vis-a-vis immobilized L-AI was studied. For both types, optimum pH was 6.0 and temperature was 50 °C. The packed bed reactor was also designed for continuous conversion of d-galactose to d-tagatose. d-Galactose derived from whey was used as substrate for the synthesis of d-tagatose by free and immobilized L-AI. The free as well as immobilized L-AI in the reactor achieved the equilibrium conversion of 50% at standard conditions. In addition, the L-AI in packed bed reactor showed conversion of d-galactose into d-tagatose for multiple cycles.