Immobilization of fungal α-galactosidase on magnetic nanoparticles and hydrolysis of raffinose family oligosaccharides (RFO) in soymilk

Abstract

Immobilization of enzymes is a very attractive technique to develop efficient and cost-effective bioprocesses. In present investigation, immobilization of partially purified α-galactosidase from Penicillium aculeatum APS1 (APS1αgal) was carried out on chitosan coated magnetic nanoparticles, Fe3O4. Immobilization conditions such as enzyme concentration, amount of chitosan coated magnetic nanoparticles (CMNP), pH and time for immobilization were optimised and maximum immobilization yield of 45 ± 2% and activity yield of 47 ± 3% were achieved. Immobilized particles were characterised by thermal analysis and Fourier transform infrared spectroscopy (FT-IR). The surface morphology of particles was studied by scanning electron microscopy (SEM). Moreover, biochemical properties of free and immobilized enzymes were compared. Thermostability and storage stability of APS1αgal were found to be improved after immobilization. Reusability of immobilized APS1αgal was assessed and it was found to retain 65% activity after 12 consecutive cycles. Further experiments were conducted to assess the ability of immobilized APS1αgal for removal of raffinose family oligosaccharides (RFO) in soymilk. During batch hydrolysis, about 80% removal of RFO was achieved. Hydrolysis of RFO was confirmed by TLC analysis. Immobilized APS1αgal was able to carry out hydrolysis of RFO up to 45% even after 7 cycles. Overall, results of this study show the potential of immobilized APS1αgal for efficient removal of non-digestible RFO in soymilk.