Preparation Of Diacylglycerol From Esterification Of Fatty Acid Catalyzed By Phospholipase A1

Diacylglycerol (DAG) is an important ingredient of the functional edible oils which shows benifits of antiobesity and lowering the postprandial blood sugar. Production of diacylglycerol by esterification of free fatty acid (FFA) with glycerol (Gly) catalyzed by phospholipase A1 (Lecitase Ultra) was investigated in this work, and a high temperature gas chromatography method was developed for analyzing FFA and mono-(MAG), di-(DAG) and triglycerides (TAG) obtained by the soybean oils. The crude diacylglycerol from the optimal conditions was molecularly distilled.The conditions including reaction time (2-10 h), water content (2-14 wt-%, FFA and Gly mass), enzyme load (10-120 U/g, FFA and Gly mass), reaction temperature (30-70℃) and mole ratio of Gly to FFA (0.5-2.5) were studied using single-factor experiment and response surface methodology (RSM). The optimal conditions were obtained as follows:40℃reaction temperature,8 wt-% water content,8 h reaction time,2.2 molar ratio of Gly to FFA, and an enzyme load of 90 U/g. Under these conditions, the esterfication efficiency (EE) of free fatty acids was 81.12%.A high temperature gas chromatography method was developed for analyzing FFA and MAG, DAG and TAG obtained by the soybean oils. The total analysis time for acylglycerols was optimized within 10 min. The method took retention time as the quality method and external standard as the quantity method which turned out to be correct. The calibration curves of FFA,MAG,DAG,TAG built by the high temperature gas chromatography shows a good linear at concentrations in range of 0.5～20.0 mg/mL. Recovery experiments show the average recoveries of samples are in range of 95.69～105.78% with RSD in range of 0.27～2.98%.After settled to separate into two layers, The crude DAG from the optimal conditions was molecularly distilled at 170℃evaporator temperatures to produce a diacylglycerol-enrich oil (DEO) with a purity of 83.1% and a yield of 42.7%, respectively, the unreacted FFA and byproduct of MAG of the oil layer of reaction mixture were removed. DAG content and FFA composition of the heavy phase and the light phase from molecular distillation was analyzed.