Preparation of magnetic dialdehyde starch-immobilized phospholipase A₁ and acyl transfer in reflection

In this paper, using a coprecipitation method to prepare Fe₃O₄ magnetic nanoparticles (Fe₃O₄ MNPS), magnetic dialdehyde starch nanoparticles with immobilized phospholipase A₁ (MDSNIPLA) were successfully prepared by using green dialdehyde starch (DAS) instead of glutaraldehyde as the crosslinking agent. The Fe₃O₄ MNPS was characterized by infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), the Brunauer-Emmett-Teller (BET) surface area analysis method, thermogravimetric analysis (TGA), and transmission electron microscopy (TEM) et al. The results showed that the alkaline resistance and acid resistance of the enzyme were improved after the crosslinking of DAS. After repeated use (seven times), the relative activity of MDSNIPLA reached 56 %, and the magnetic dialdehyde starch nanoparticles (MDASN) had good carrier performance. MDSNIPLA was applied to enzymatic hydrolysis of phospholipids in the soybean oil degumming process. The results showed that the acyl transfer rate of sn-2-HPA was 14.01 %, and the content of free fatty acids was 1.144 g/100 g after 2 h reaction at 50 °C and pH 5.0 with appropriate boric acid. The immobilized enzyme has good thermal stability and storage stability, and its application of soybean oil improves the efficiency of the oil.