Sequential Alcoholysis–Esterification Catalysis by Immobilized Lipases for the Synthesis of OPO Structured Lipids: Immobilization Methods, Carriers, and Prospects

OPO structural lipids (1, 3-dioleoyl-2-palmitoylglycerol) are the most abundant type of triglycerides in breast milk. They are beneficial for providing energy and calcium absorption for infants and can prevent constipation caused by the formation of insoluble calcium soaps. Currently, enzymatic synthesis of OPO mainly involves three routes: acid hydrolysis, ester exchange, and alcoholysis–esterification combined catalysis. The acid hydrolysis process completes in one step, and the product separation is simple, but it is limited by the migration of acyl groups, resulting in generally low OPO yields. The ester exchange process uses both the substrate and product as triglycerides, and the subsequent separation is costly. In contrast, lipase, as an oil–water interface enzyme, has higher activity in oil–water systems, and the combined catalytic route of first alcoholysis to prepare 2-monoglyceride and then esterification to introduce oleic acid is more likely to achieve a higher OPO yield. However, in the process of enzymatic synthesis of OPO, free lipases have the disadvantages of poor thermal stability, easy inactivation, and difficulty in recovery, and immobilization is a key strategy to improve their industrial applicability in combined processes. This paper focuses on the research progress of immobilized lipases in the enzymatic synthesis of OPO structural lipids, systematically reviews the principles, advantages, and limitations of the main immobilization methods, and compares the performance of carrier systems in terms of enzyme loading, catalytic activity, operational stability, and reusability. Finally, this paper looks forward to future directions such as composite immobilization strategies, multi-enzyme combined catalytic systems, and rational design of carrier structures, with the aim of providing theoretical references for the efficient and green enzymatic synthesis of OPO structural lipids.