Enzymatic interesterification of soybean oil and methyl stearate blends using lipase immobilized on magnetic Fe3O4/SBA-15 composites as a biocatalyst.

The magnetic Fe3O4/SBA-15 composites were prepared, and treated with 3-aminopropyltriethoxysilane as a carrier material for enzyme immobilization. The immobilization of Candida rugosa lipase onto the amino-functionalized Fe3O4/SBA-15 composite was investigated by using glutaraldehyde as a coupling reagent. The immobilized lipase was then employed as a biocatalyst for the interesterification of soybean oil and methyl stearate in a laboratory-scale operation at 45°C. Various techniques, such as Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), and vibrating sample magnetometry (VSM), were used for the characterization of the immobilized lipase composite. The immobilized lipase behaved superparamagnetic and showed excellent response at applied magnetic field. The obtained results showed that the immobilized lipase could efficiently catalyze the interesterification reaction. Moreover, the interesterification reaction parameters, such as reaction temperature, substrate ratio and reaction time were investigated regarding the stearoyl incorporation into the triacylglycerols. Further, the immobilized lipase proved to be easily separated from the reaction mixture by applying an external magnetic field and to be stable in the repeated use for four cycles.