Simultaneous Partitioning and Enrichment of PUFAs in Algal Oil via Enzymatic Hydrolysis and Decarboxylation Based on an Innovative Ionic Liquid Three-Phase System

Microalgal oil represents a sustainable source of polyunsaturated fatty acids (PUFAs), essential nutrients with significant health implications. This study introduces an innovative ionic liquid three-liquid phase system (IL-TLPS) to simultaneously convert non-PUFAs into biofuels and concentrate PUFAs, addressing nutritional, energy, and environmental concerns. The IL phase effectively facilitated substrate oil interaction, substantially reducing particle size. This reduction augmented the interfacial area between the substrate oil and the CvFAP-containing aqueous phase, promoting efficient fatty acid separation and PUFA recovery from free fatty acids (FFAs). A tandem hydrolysis–decarboxylation–rehydrolysis process, coupled with the IL-TLPS, reduced the FFA content from 18.74% to 4.91%. Subsequently, secondary hydrolysis of the decarboxylated algal oil increased the PUFA content in the upper phase from 48.86% to 56.89%, with 38.59% PUFAs concentrated in the IL phase. Distillation facilitated the separate recovery of PUFAs and alkane compounds, enabling classified ester applications and graded PUFA utilization; PUFA content in glycerides increased to 83.79%. Notably, the IL-TLPS intermediate phase, functioning as a liquid immobilized enzyme, retained over 90% catalytic activity across multiple cycles, demonstrating exceptional reusability. This study thus establishes a novel, efficient, and selective methodology for microalgal oil resource utilization.