Immobilization of soybean (Glycine max) α-amylase onto Chitosan and Amberlite MB-150 beads: Optimization and characterization

α-Amylase from soybeans was immobilized on two different matrices, Chitosan beads and Amberlite MB-150. Maximum immobilization of 62% and 70.4% was obtained with Chitosan and Amberlite MB-150, respectively. The optimum pH obtained was 8.0 and 7.0 for the α-amylase immobilized on Chitosan beads and Amberlite MB-150, respectively; free enzyme showed an optimum pH of 5.5. The optimum temperature for both free and Chitosan immobilized enzymes was 70 °C whereas it was 75 °C for enzyme immobilized on Amberlite MB-150. α-Amylase immobilized on Chitosan showed an apparent Km of 4 mg/mL, whereas Amberlite immobilized enzyme showed an apparent Km of 2.5 mg/mL. The immobilized enzyme showed a high operational stability by retaining 38% and 58% of initial activity after 10 uses for Chitosan and Amberlite, respectively. The easy accessibility of soybean α-amylase, the ease of its immobilization on low-cost matrices, increased stability upon immobilization make it a suitable product for future applications. Both the matrices used for enzyme immobilization are non-toxic, cheap, renewable, biodegradable and have importance in food, cosmetics, biomedical, or pharmaceuticals applications.