Immobilization of Pectinex Ultra SP-L to produce galactooligosaccharides

Pectinex Ultra SP-L, a commercial enzyme preparation obtained from Aspergillus aculeatus, containing β-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.