Reduction of flatus-inducing factors in soymilk by immobilized alpha-galactosidase

Abstract

?-Galactosidase from Aspergillus oryzae was immobilized on chitosan beads using glutaraldehyde as a cross-linking agent. The general properties of free and immobilized enzymes were determined. The optimum pH for the free and immobilized enzymes was 4.8 and 4.6 respectively. The optimum temperature for the free enzyme was 50 °C, whereas that of immobilized enzyme was increased to 56°C. Kinetic parameters were determined with synthetic substrate (p-nitrophenyl ?-D-galactopyranoside) and raffinose. Immobilized enzyme showed a higher Km and a lower Vmax than the free enzyme. The immobilized enzymes were used in batch, repeated and continuous mode. A level of 92% hydrolysis was observed at a flow rate of 60 ml/h. The immobilized enzyme was used repeatedly ten times without any change in the performance of the immobilized enzyme in fluidized-bed reactor. The results obtained are of considerable interest for industrial purposes. © 2006 Portland Press Ltd.