Study on the Deacidification of Rice Bran Oil Esterification by Magnetic Immobilized Lipase

Candida antarctica lipase B (CALB) was immobilized on Fe3O4/SiOx-g-P (GMA) polymer carrier to obtain nano-magnetic Fe3O4/SiOx-g-P (GMA) lipase (magnetic enzyme). The obtained magnetic enzyme particles had an enzyme protein loading of 98.7 mg/g, an enzyme activity of 1226.5 U/g, an average particle diameter of 100.5 ± 1.30 nm, a magnetization of 15.80 emu/g, a magnetic enzyme optimum pH of 7.0, and an optimum temperature of 50 °C. The prepared magnetic enzyme was used as a catalyst, phytosterol was esterified with free fatty acid (FFA) in rice bran oil (RBO). Under the conditions of pH was 7.0, the FFA/phytosterol molar ratio was 1:4, the dosage of the immobilized CALB was 10.0%, the esterification temperature was 50 °C, the esterification time was 72 h, and the molecular sieve addition was 8.0%. The FFA content in RBO decreased from 16.0 to 2.4%, and the conversion rate of phytosterol was 85.7%. When the magnetic enzyme was used repeatedly for 7 times, the relative enzyme activity of the magnetic enzyme was 83.0%, which improved the utilization efficiency of the enzyme.