Production of Fungal α‐Galactosidase and Its Application to the Hydrolysis of Galactooligosaccharides in Soybean Milk

Abstract

ABSTRACT Production of extracellular α‐galactosidase of Aspergillus oryzae was induced remarkably well by the addition of soybean carbohydrate to culture medium. Addition of stachyose or raffinose induced slight production. Soybean carbohydrate, stachyose, and raffinose also served well for the synthesis of invertase. Maximum hydrolysis of p‐nitrophenyl‐α‐D‐galactopyranoside (PNPG) by the enzyme occurred at pH 4.0, and optimum temperature for hydrolysis of PNPG was 50° C. The enzyme seemed to be stable from 30‐50° C. The mixture of α‐galactosidase and invertase totally hydrolyzed raffinose and stachyose at 50° C, pH 4.0 in 2 hr. The mixed preparation of the enzyme substantially hydrolyzed galactooligosaccharides in soybean milk at 50° C, pH 6.3 in 2 hr.