Immobilization of Pectinex Ultra SP-L to produce galactooligosaccharides

Abstract

Pectinex Ultra SP-L, a commercial enzyme preparation obtained from Aspergillus aculeatus, containing -galactosidase activity,was immobilized onto Eupergit C and was used for the production of galactooligosaccharides (GOS). Immobilization resulted in 100% binding yield and higher GOS yield (24%, w/v) with respect to soluble enzyme. Optimum conditions were not affected by immobilization, and optimum pH and temperature for free and immobilized enzyme were 4.0–5.0 and 55–60 ?C, respectively. Immobilized enzyme was more stable at high pH and temperatures. The amount of GOS produced from 30% (w/v) lactose solution using the free and immobilized enzyme was determined to be 12.8 and 15.8% (w/v) of the total sugar in the reaction mixture, respectively. The kinetic parameters for the free and immobilized enzyme were also determined. The immobilized Pectinex Ultra SP-L could be used for the production of galactooligosaccharides, since the immobilization yield is high (124%) and immobilized enzyme retains its activity for 20 days without any decrease.