Solvent-free synthesis of diacylglycerols via enzymatic glycerolysis between edible oils and glycerol catalyzed by self-made immobilized lipase PS@LXTE-1000

Abstract

Diglycerol (DAG) is a structural lipid with the functions to lower body fat accumulation and decrease serum triglyceride level. However, the enzymatic synthesis of DAG is limited by the high-efficient and economic lipases. In this paper, the immobilized lipase PS@LXTE-1000 was self-made by immobilizing the Pseudomomas cepacian lipase on to the hydrophobic microporous resin LXTE-1000. The results indicate that LXTE-1000 was a uniform mesoporous sphere with the mean diameter of 400 ​μm, pore size of 14.6 ​nm, pore volume of 0.5 ​cm³/g and surface area of 126.0 ​m²/g, showing superior structural properties for lipase immobilization. Under the optimal reaction conditions with the molar ratio of rapeseed oil to glycerol being 1:1, adding amount of immobilized lipase being 4%, reaction at 50 ​°C, the highest DAG content of 46.7% was achieved in 3 ​h via enzymatic glycerolysis catalyzed by LXTE-1000. After 7 cycles of reuse, the self-made LXTE-1000 could still retain 78.3% of its initial catalytic ability. Besides, LXTE-1000 was observed to facilitate the DAG production via glycerolysis reaction between glycerol with other seven edible oils including corn oil, sesame oil, peony seed oil, rice bran oil, peanut oil, soybean oil and flaxseed oil. Specifically, the glycerolysis reaction with sesame oil, peony seed oil and rice bran oil even led to the DAG content of 52.1%, 53.3% and 51.2%, respectively, Hence, this paper provide a novel strategy to produce high-efficient and economic immobilized lipases, which shows great potential in the green synthesis of functional lipids such as DAG.