Pullulan-complexed α-amylase and glucosidase in alginate beads: Enhanced entrapment and stability

• High entrapment of α-amylase and glucoamylase mixed with pullulan in alginate beads.
• High thermal and pH stability of beads of enzymes–pullulan complex.
• Efficient release of glucose from starch using beads of enzymes–pullulan complex.
• Enhanced reusability of enzymes entrapped in alginate beads.

Enhanced entrapment of the enzymes, α-amylase and glucoamylase, was found in alginate beads on addition of pullulan in the enzyme mixture. Under optimized process conditions of entrapment, enzymes–pullulan complex showed an entrapment of 85% in the alginate beads as opposed to 25% for the free enzymes. Beads of enzymes–pullulan complex showed lower inactivation rate constant and higher half life than corresponding beads of free enzymes. Activation energy of beads of enzymes–pullulan was increased by 6.81 kJ/mole compared to beads of free enzymes. This implies better stability the enzymes in enzymes–pullulan beads along with increased immobilization yield. Moreover, enzymes–pullulan beads also showed pH stability at extreme acidic and alkaline pH. Addition of pullulan in the enzymes mixture lowered the Km and increased the Vmax as compared to beads of free enzymes. Hydrolysis of starch and reusability study showed better applicability of beads of enzymes–pullulan as compared to free enzymes.