Calcium alginate entrapped preparation of Alpha-galactosidase: Its stability and application in hydrolysis of soymilk galactooligosaccharides

Abstract

Thermostable ?-galactosidase from Aspergillus terreus GR was insolubilized using concanavalin A obtained from jack bean extract and in order to maintain the integrity of complex in the presence of its substrate or products, this complex was crosslinked with glutaraldehyde. Soluble ?-galactosidase entrapped in calcium alginate retained 82% of enzyme activity whereas, Con A-?-galactosidase complex entrapped in calcium alginate and crosslinked Con A-?-galactosidase complex entrapped calcium alginate retained 74 and 61% activity, respectively. A fluidized bed reactor was constructed for continuous hydrolysis of galactooligosaccharides in soymilk using crosslinked Con A-?-galactosidase complex entrapped calcium alginate. Optimum conditions such as pH (5.0) and temperature (65°C) were the same for all immobilized enzyme preparations and soluble enzyme. Crosslinked Con A-?-galactosidase entrapped complex exhibited enhanced thermostability and showed 62% of activity (38%) after 360 min at 65°C. Entrapped crosslinked Con A-?-galactosidase complex preparation was superior in the continuous hydrolysis of oligosaccharides in soymilk by batch processes compared to the other entrapped preparations. The entrapped crosslinked concanavalin A-?-galactosidase complex retained 95% activity after eight cycles of use. © 2010 Society for Industrial Microbiology.