Cost effective surface functionalization of silver nanoparticles for high yield immobilization of Aspergillus oryzae β-galactosidase and its application in lactose hydrolysis

► AgNPs were synthesized, characterized and surface modified by glutaraldehyde. ► Aspergillus oryzae β galactosidase was adsorbed on unmodified and modified AgNPs. ► Immobilized enzyme was used for hydrolyzing whey and milk lactose. ► Operational stability of immobilized β galactosidase was also investigated.