preparation of nanomagnetite/soy protein isolate as a suitable carrier by cold gelation method for inulinase enzyme immobilization

Nowadays, enzyme immobilization on the nano carriers was applied in food industry. In this study, Inulinase enzyme was immobilized on the magnetite nanoparticles functionalized with protein nanoparticles through covalent attachment. Inulinase can produce high fructose syrup from inulin in a one-step enzymatic process. The Inulinase was immobilized in order to increase enzyme stability under extreme conditions of industrial processes, reusability, reduce the risk of environmental pollution with the enzyme protein, reducing the cost of the final products and the ability of using bioreactors with immobilized enzyme in continuous system. In addition, the immobilized enzyme on the magnetite nanoparticles can be separated from the reaction medium by a magnetic field and it is not necessary to use of other uneconomical methods such as centrifugal separation and filtration. Therefore, in the first step, the magnetite nanoparticles were prepared by co-precipitation method. Then, in the second step, the soy protein isolate nanoparticles were synthesized by cold gelation method and then the magnetite nanoparticle’s surface was coated for modification and stabilization. In the third step, the enzyme was immobilized on the magnetite carrier through covalent attachment via glutaraldehyde. In this study, scanning electron microscope (SEM), dynamic light scattering (DLS) and fourier transform spectroscopy (FTIR) were used for analyze the particle size, shape, morphology and functional characteristics of magnetite nanoparticles and enzyme immobilization in all steps of preparation. Based on the SEM results, the size of nanomagnetite were in the range of 20 to 50 nm with the mean diameter of about 35 nm. The nanomagnetite obtained possessed spherical morphology, uniformly distributed. The size of soy protein isolate (SPI) nanoparticles according to the initial SPI amount (gr %) were in the range of 100-600 nm by using DLS technique. FTIR method confirms proper enzyme immobilization on the functionalized nanomagnetite by protein.