A new strategy for magnetic immobilized phospholipase A1 and its application in soybean oil degumming: Multipoint covalent binding

In order to achieve better degumming of crude soybean oil and reduce the phosphorus content in oil, a method of multipoint immobilized phospholipase A1 (PLA1) was proposed for degumming. PLA1 with a high enzymatic load and good stability was magnetically immobilized on a modified aldehyde-rich chitosan carrier by changing the pH. The aldehyde content of the activated carrier reached 288 mu mol/g. The optimal conditions of the magnetic carrier and PLA1 multi-point covalent binding were as follows: PLA1 additive amount 6000 U/ml, group ratio 7:1, reaction at 50 degrees C for 3.0 h. According to the characterization analysis, PLA1 was essentially spherical with good dispersion, the particle size was 83 nm, and the XRD pattern was similar to the conventional one. After functional group analysis, spectral peaks, such as C--O and Fe-O, appeared, which proved that PLA1 was suc-cessfully fixed on the carrier with a saturation magnetization of 23.68 emu/g. The optimum temperature of covalent and multipoint immobilized PLA1 was 60 degrees C, with an optimum pH of 7.0 and 6.5 and an enzyme loading of 115 and 128 mg/g, respectively. The phosphorus content was 35.09 mg/kg by multipoint immobilized PLA1. After eight cycles of repeated use, the relative activity of the immobilized PLA1 was still more than 80%.