Whey protein isolate for the preparation of covalent immobilization beads

Whey protein isolate (WPI) was employed, for the first time, to activate carrageenan (Car) beads for the covalent immobilization of the Aspergillus oryzae β-D-galactosidase (β-gal). These Car beads were subjected to a WPI treatment step followed by a glutaraldehyde (GA) treatment step in order to enable such covalent immobilization. The WPI treatment was optimized via the Box-Behnken Design (BBD). The BBD anticipated that treating the Car beads with a 2.36% WPI solution of pH 5.25 for 7.04 h would allow for the attainment of an immobilized β-gal's activity recovery percent of 34.43%. A verification experiment was accomplished while employing the abovementioned conditions and an immobilized β-gal's activity recovery percent of 34.80 ± 1.11% was attained. It was also shown that the immobilization of β-gal onto the GA-WPI treated Car beads did not alter the enzyme's optimum temperature or optimum pH. Moreover, a reusability study was conducted and 93.84 ± 0.72% of the immobilized β-gal's initial observed activity was preserved during the 13th reusability cycle.