Study On Synthesis Of Diacylglycerol By Lipase-catalyzed Glycerolysis

Diacylglycerol (DAG) functional edible oil is novel type of oil with unambiguousnutritional characteristics of the prevention of obesity and the decrease in postprandial serumtriacylglycerols (TAG), producted by enzymatic modification of natural edible oil.Diacylglycerol edible oil is safe in-use and can be used as upgrade and update products ofnormal edible oil, to radically relieve the actuality of increasingly prevalence rate of chronicdiseases of Chinese, such as obesity, hyperlipidemia, diabete, et al, caused by diet structurewith high oils and energy consumption, and to regulate human sub-health level and inhibitethe generating and developing of lifestyle-related chronic diseases with no change of existingdietetic habit. The potential maket value of diacylglycerol edible oil is about50000millionyuan. Now, diacylglycerol edible oil is producted only in Japan and American, and there is noreport on industrialization of diacylglycerol edible oil in China. In September2009Japonicfactories stopped diacylglycerol oil production because glycidol fatty acid esters at levels10to200times found in their products. Some non-Econa edible oil was recalled bymanufacturer.Based on the in-depth analysis of the research status at inland and abroad, glycerolysisreaction was studied detailedly. Firstly, synthesis of diacylglycerol by lipase-catalysedglycerolysis was studied. Glycerolysis reaction in ter-betanol can be used to product highpurity diacylglycerol (97.9%) in laboratory scale because of the high conversion of TAG(98.7%). However, a glycerolysis reaction in an organic solvent also is unsuitable forindustrial production. The practicality of glycerolysis reaction in a solvent free system toproduct diacylglycerol oils was studied. Lipozyme RM IM can be used in glycerolysisreaction in a solvent free system to product diacylglycerol (DAG content was no less than55%) when the glycerol loadge was low (TAG/glycerol was1:1, mol/mol). Furthermore,Lipozyme RM IM was unstable because of free glycerol, glycerol must be adsorbed on silicagel before starting the reaction so as to achieve high yield and good operational stability,which is also unsuitable for large-scale industrial production. Three commercial immobilizedlipases, Lipozyme RM IM, Lipozyme TL IM and Novozym435, were screened for the production of DAGin a packed-bed reactor. Novozym435showed the best performance (DAG content was 55.02%in glycerides) and was selected to catalyze the glycerolysis reaction with abundantglycerol (glycerol/TAG2:1) in a solvent free system. It was proved that diacylglycerol oilscan be producted in this was after scale-up reaction (the mixture of substrate was20Kg) wasstudied in a packed-bed reactor. To reduce the production cost of DAG oil, Lipozyme TL100L was immobilized on resins and used to catalyzed glycerolysis reaction in a packed-bedreactor, mixture of glycerides with DAG54.64%, MAG17.47%, TAG27.89%was obtained.A diacyglycerol oil (DAG content was65.11%, TAG content was34.89%) was product afterpurification by molecular distillation. DAG oil with good physico-chemical properties wasobtained after decolor and deodorization, glycidol fatty acid esters content was0.747ppm.MAG producted in the glycerolysis reaction can be used to product DAG oil (with TAG)through esterification with oleic acid catalyzed by a novel partial glyceride lipase (LipaseSMG1).A set of diacylglycerol oil production process was established by combination ofholoenzymatic process (glycerolysis reaction in a packed-bed reactor), molecular distillation,and oil refining technology. The successive scale-up of diacylglycerol production usingholoenzymatic process from laboratory-scale (gram scale) to pilot-scale (kilogram scale) wascarried out successfully, basing on the early research in lab. A diacylglycerol oil productionprocess that can be industrialized was devoleped, and no less than60%purity of theserialization diglyceride products, which measure up to national related standard and havequalification to sale promotion in the market, can be gained with the lower cost. Thisproduction process, which had the advantages of higher reaction efficiency, simpler processoperation, excellent repeatability of reaction, lower operating costs, et al, was a preferencemethod to synthesize a series of diacylglycerol product with more than60wt%diacylglycerolcontent and has reached the leading domestic and international advanced level.