Separation And Purification Of Diacylglycerol By Molecular Distillation

Diacylglycerol is a kind of structure lipid with physiological activity and as natural trace components of various sources of edible oils, which is widely used in food, medicine and chemical industry, with good prospects for industrial applications.In this study, diacylglycerol was separated by molecular distillation technology from palm oil as raw material, and various factors affecting the laboratory molecular distillation was discussed. On the basis of the laboratory, the pilot test was conducted, and a variety of factor affecting the pilot test was discussed. Lastly the indicators of diacylglycerol products were measured, and their oxidation stability was preliminary explored. By discussing the factors of laboratory molecular distillation process, the suitable process condition of separating diacylglycerol was determined: pressure was 0.1Pa, wiper speed was 285 r/min, feed rate was 0.4 L/h, distillation temperature was 220 ?, and the mass fraction of diacylglycerol of the product could reach 85.97%, wherein the ratio of 1,3-DAG and 1,2-DAG was 2.78:1. Through studying the factors affecting the pilot test process, the appropriate process condition of separating diacylglycerol was determined:0.01 Pa,distillation temperature 220?, wiper speed 200 r/min, feed rate 10 L/h, diacylglycerol purity of the light phase product was 93.39%, wherein the ratio of 1,3-DAG and 1,2-DAG was 2.49:1. In both experiments, the most influential factor is temperature, followed by the feed flow rate. After tested, the product reached diacylglycerol oil standards. Compared with palm oil, fatty acid composition of diacylglycerol product unchanged. Saturated fatty acids increased, and unsaturated fatty acid ratio decreased, so the stability of diacylglycerol was improved.The results about physicochemical properties of diacylglycerol product indicate that diacylglycerol product has an acid value of 6.0 mgKOH/g, a peroxide value of 2.5 mmol/kg, a saponification value of 183.5 mg KOH/g, an iodine value of 44.7g I2/100 g. The saponification value and iodine value of diacylglycerol product decreased compared with palm oil: the reason was related to the ratio of saturated fatty acids increasing. diacylglycerol product was clear and transparent, with odorlessness and good taste, which was in line with national standards; diacylglycerol products of trans fatty acids were detected by GC, the products contained both trans oleic acid and trans linoleic acid, with respect to trans-linoleic acid, the content of trans oleic acid was higher, the content of trans oleic acid and trans-linoleic acid were up to 2.45% and 0.58% respectively. The content of trans fatty acid of all the diacylglycerol products were less than 5% in accordance with the national standards; the content of campestero, stigmasterol and ?-sitosterol in the palm oil was 6.01?6.81 ?22.75 mg/100 g, respectively; the content of campesterol, stigmasterol and ?-sitosterol in diacylglycerol products was 351.47?273.64?1027.42 mg/100 g, respectively. Among three sterols, thecontent of ?-sitosterol was the highest. The total content of three sterols was up to 1652.53 mg/100 g. The content of the sterol in the heavy component product was very low, which indicated most of three sterols were all distilled into the light phase product namely diacylglycerol product, and increased the physiological function of diacylglycerol product; by measuring the induction time of the palm oil?the light phase product and the heavy phase, as could be seen the induction time of the light phase product(diacylglycerol) was lower than the induction time of palm oil and the heavy phase product, which indicated with respect to the palm oil and the heavy phase product, the oxidation stability of diacylglycerol product was worse, and the shelf life was shorter,which needed to add antioxidants to enhance the antioxidation ability.Through calculating material and heat of the pilot molecular distillation process and designing process, the cost of products and the technology economic was estimated and analysised indirectly to select the appropriate amount of process and provide the theoretical and scientific basis for separating diacylglycerol of molecular distillation,which provided reliable reference for the current oil processing industry.