Enzymatic degumming of soybean oil with magnetic immobilized phospholipase A2

• Highest enzyme loading and enzymatic activity were obtained in PLA2-Fe3O4/SiOx-g-P(GMA).
• Residual phosphorus content and free fatty acids content were 9.7 mg/kg and 0.84 g/100 g.
• PLA2 can hydrolyze Sn-2 ester bond of phospholipids without acyl migration.
• The problem of the high free fatty acid content and low efficiency could be solved.
• The magnetic immobilized PLA2 still possessed more than 80% of its initial activity.

In this study, magnetic immobilized phospholipase A2 (PLA2) was used to degum soybean oil such as magnetic particles crosslinked with sodium alginate PLA2 (PLA2-MPCSA), Magnetic chitosan microparticles containing PLA2 (PLA2-MCM), Fe3O4/P(GMA-EDGM-St) PLA2, and Fe3O4/SiOx-g-P(GMA) PLA2, successfully improving the recycling aspect of the degumming process. The highest enzyme loading and enzymatic activity (122.60 mg/g and 1289 U/g, respectively) were obtained using the magnetic immobilized PLA2-Fe3O4/SiOx-g-P(GMA) system. Compared to free PLA2, magnetic immobilized PLA2 had a broader pH-activity profile (pH 4.0–5.5) and activity remained stable between 50 and 70 °C. Enzymatic degumming with PLA2-Fe3O4/SiOx-g-P(GMA) was carried out over 5.0 h with an enzyme dosage of 0.24 g/kg, a pH of 5.0, and a temperature of 55 °C, resulting in residual phosphorus and free fatty acid contents of 9.8 mg/kg and 0.84 g/100 g, respectively. Moreover, magnetic immobilized PLA2 retained more than 80% of its initial activity even after 5 cycles of soybean oil degumming.