Production of á-Galactosidase by Aspergillus oryzae through solid-state fermentation and its application in soymilk Galactooligosaccharide hydrolysis

á-Galactosidase was produced by Aspergillus oryzae on red gram plant waste-wheat bran based media in solid-state fermentation (SSF). Optimum temperature for á-galactosidase production was 35 0C and upto 4 cm of bed height of substrate had no inhibitory effect on enzyme production. Hydrolysis of galactooligosaccharides in soymilk was carried out by á-galactosidase. Optimum temperature and pH for the hydrolysis of raffinose and stachyose of soymilk were 55(0)C and 5.2-6.2, respectively. The enzymatic treatment for 3 h completely removed the raffinose oligosaccharides in soymilk. Crude extract also showed considerable amount of invertase activity.