Co-immobilization of bi-lipases on magnetic nanoparticles as an efficient catalyst for synthesis of functional oil rich in diacylglycerols, phytosterol esters and α-linolenic acid

A novel method for one-pot synthesis of functional oil rich in diacylglycerols (DAGs), phytosterol esters (PEs) and α-linolenic acid (ALA) was developed. Firstly, candida rugosa lipase (CRL) and thermomyces lanuginosus lipase (TLL) were co-immobilized on polydopamine coated Fe3O4 nanoparticles (PDA@Fe3O4 NPs) via covalent bonds. The prepared co-immobilized bi-lipases (CRL/TLL-PDA@Fe3O4) displayed excellent thermal stability, catalytic activity and reusability in comparison to the free forms. Then a rapid one-pot enzymatic synthesis of functional oil was conducted by using CRL/TLL-PDA@Fe3O4 as the biocatalyst. Three kinds of functional oils were produced with high DAGs, PEs and ALA content (≥30.09%, ≥15.61% and ≥26.45%, respectively) under the optimized conditions (1:3:2 phytosterols/ALA/triglycerides, 20 mg/mL CRL/TLL-PDA@Fe3O4, 40 °C, 8 h). In comparison to a two-step (sequential/immobilized monolipase) synthesis, a significantly synergistic effects occurred in the co-immobilized bi-lipases system. The results demonstrated the feasibility of the novel strategy and would be helpful for the oils and fats industry.