Research For Enzymatic Synthesis Process Of Polyunsaturated Fatty Acid Structure

Oil not only gives the unique flavor to food, but also plays an important physiological fuction in the human body. The main form of natural oils is triglycerides. The length, saturation and positional distribution in glycerol skeleton of fatty acids, all of them can affect the physicochemical properties and physiological function of glycerides. According to the characteristics of fat metabolism in human body, more and more researchs were to synthetic structure oil which is to meet the needs of the people of flavors, colors, nutrition and health care.1. This study adopts the low temperature solvent crystallization to enrichment polyunsaturated fatty acids (PUFA) glycerides, the fatty acid composition of raw algae oil is the twenty-two carbon acid six (DHA) 41%, the twenty-two carbon acid five (DPA) 10%, palmitic acid (P) 42% and other saturated fatty acid (fourteen, fifteen, seventeen, eighteen acid) 7%. The optimal crystallization conditions for-80℃ static crystal 4 days, ratio of the volume and quality of acetone and algal oil is 30 (v/wt, mL/g). The composition of fatty acids after the enrichment of PUFA (DHA and DPA) glycerol esters is PUFA 80.9%, P 19.1%, excluding other saturated fatty acids. The PUFA content of fatty acid composition in the algal oil’s sn-2 position increased from 74.8% to 92.2% by this enrichment method.2. In this study uses acidolysis, the PUFA after enrichment from algal oil and capric acid as substrate, to synthesis glycerol structured oil which rich decanoic acid in sn-1/3 position and PUFAs in sn-2 position. This chapter studys the main factors affecting the acid hydrolysis reaction (enzyme, enzyme dosage, substrate molar ratio, reaction temperature and time), and to determine the best condition of reaction were:lipase Ls-20 which is from our experimental group as the catalyst, hexane as solvent, the molar ratio of fatty acid and glycerol is 10/1, the quality of enzymes is 10% of glycerol, nitrogen gives protection,40℃,180rpm,25h. The compositon of fatty acid in products glycerol is decanoic acid 33.9%, PUFA 60.6%, P 4.8%; the PUFA’s content in sn-2 positon is 78.1%; and the capric acid’s content in sn-1/3 position is 51%. The reaction had synthesised structured oil which riched decanoic acid in sn-1/3 and PUFA in sn-2.3. This study compared the alkali neutralization, liquid-liquid extraction and low temperature crystallization that three kinds of separation methods. Finally this reseach decided to use low temperature crystallazition to purificate the acid hydrolusis products because of the highest recovery of glycerol. We investigated the effect of the quality and volume ratio of oil and actone on the crystallization, the final results showed that when the temperature under-20℃ for 24h, the quality and volume ratio of oil and actone is 1/1.6 (wt/v, g/mL), the separation of liquid phase and solid phase will be the best. The glyceride’s composition in liquid phase is 89%, the fatty acid’s is 11%. The glyceride’s recovery rate is 78.7%.