A highly efficient and recoverable enzymatic method for removing phospholipids from soybean oil via an ionic liquid-based three-liquid-phase

Abstract

A three-liquid-phase system (TLPS) with the ionic liquid (IL) constituting one of the phases was developed and used as a novel enzymatic reaction and separation system to remove phospholipids from crude soybean oils. Among the TLPSs tested, the oil/[BMIM]BF4/sodium citrate TLPS was considered to be the optimal system. In this system, a novel emulsion containing two different emulsion structures (W1/W2 and W2/O/W2 emulsion, W1 and W2 represent the IL-enriched and salt-enriched phase, respectively) could be formed, giving rise to its high catalytic efficiency. In this emulsion, not only could the phospholipids at the top/middle interface be hydrolyzed, but the hydrolysis of phospholipids also occurred at a higher efficiency at the middle/bottom interface where the interface area was much larger than the top/middle interface. As a result, the enzymatic treatment time in the TLPS (3 min) could be shortened by 60-fold relative to the conventional O/W system (3 h). Furthermore, the phospholipase in the salt-enriched phase could be reused for at least 8 batches without a significant loss in catalytic efficiency. This TLPS could offer a cost-effective, easily scaled up, and low-energy cost system for the reaction of weak polar substrate catalyzed by an interfacial enzyme.