Enzymic degradation of raffinose family oligosaccharides in soymilk by immobilized alpha-galactosidase from Gibberella fujikuroi

Abstract

?-Galactosidase from Gibberella fujikuroi was immobilized in polyacrylamide gel. Free ?-galactosidase showed optimal activity at pH 5.8, immobilized ?-galactosidase showed at 5.2-5.6. In between pH 4.0 and 6.3, free and immobilized ?-galactosidase showed more than 90% activity. The optimum temperature of free and immobilized ?-galactosidase was 56°C and 54-56°C, respectively. Gibberella f. ?-galactosidase retained 100% activity after 6 h incubation at 55°C. After 12 h incubation ?-galactosidase retained 90% activity. After 3 days free enzyme retained only 6% initial activity and immobilized enzyme 17% initial activity. Soymilk was treated with free and immobilized ?-galactosidase from G. fujikuroi. After 3 h incubation raffinose family oligosaccharides were reduced to 79 and 66% by free and immobilized ?-galactosidase, respectively. Immobilized ?-galactosidase can be reused four times compared to free ?-galactosidase. A fluidized reactor was designed to treat soymilk continuously. Soymilk was passed through the fluidized reactor with different flow rates and maximum reduction in raffinose family oligosaccharides determined. © 2002 Elsevier Science Ltd. All rights reserved.