Enrichment And Purification Of EPA And DHA From Marine Fish Oil

Marine fish oil is rich in polyunsaturated fatty acids,such as EPA and DHA,which has a wide range of application in food,health care and medicine,and is the important part of health care products and pharmaceuticals market.Hainan island’s fishery resources are abundant,but fish oil industry of Hainan island is still in its infancy.This research is based on the reuse of abandoned the fish guts,by extracting fish oil and concentrate EPA and DHA in fish oil,we realized the high value of fish wastes environmentally friendly,which can be referred in practical manufacturing of marine fish oil.(1)This research’s raw materials were come from a farmer’s market,fish oils were produced by enzymatic hydrolysis under physiological temperature.This research optimized the traditional saponification preparation of fatty acid,the optimal reaction condition:10 g fish oil are saponificated in NaOH(3.0 g)ethanol aqueous solution under 50℃ for 20 min.Compared to traditional methods,this preparation of fatty acid has shorter reaction time,lower reaction temperature,and can reduce the EPA and DHA loss effectively.(2)This research established the HPLC method for the determination of content of EPA and DHA in fish oil products,chromatographic conditions:XDB(C18)Agilent chromatography column,column temperature 38℃,detection wavelength of 200 nm,flow rate 1.0 mL/min,10 μL/sample,mobile phase:acetonitrile:water=85:15,EPA methyl peak is at 19.653 min,DHA methyl peak is at 24.488 min.This method is stable,accurate,and timesaving.In a mixture of fish oil,EPA’s content is 2.0%,DHA’s content is 7.6%,the total content is 9.6%,which has considerable value in development and utilization.(3)This research optimized the method of urea inclusion for the enrichment of the EPA and DHA in fish oil,in this process,four factors,time,temperature,dosage of urea and methanol are inspected through orthogonal experiment,finally the optimal conditions were checked:fatty acid(g):urea(g):methanol(mL)=2:6:48,froze for 2 h under 4℃.After enrichment process,EPA’s content became 5.47%,recovery rate was 47.86%;DHA’s content became 40.79%,the recovery rate was 93.92%;Total content was 46.26%,total recovery rate was 84.33%.EPA and DHA’s contents in the health food are generally lower than 30%,high-valued fish oil products can be produced by this process,which has considerable application prospect and practical significance.(4)In order to get fatty acids products that have higher contented EPA and DHA content products,this research adopted the enzymatic esterification method.After screening 8 kinds of lipases,finally AYS lipase was chosen.Then investigated some factors,such as the enzyme dosage,feeding condition and lauryl alcohol dosage,reaction time,enzyme solution temperature,shaking speed,were determined to obtain products contain 84%EPA and DHA^content with total recovery rate over 70%.Finally,enzyme catalytic glyceride synthesis process was attempted.The study found that lipases showed selective activities with different fatty acids.In order to explore the mechanism of selectivity in enzymatic esterification,this study used the method of molecular simulation to test the distances between AYS lipase’s active center and fatty acids when they are docked,in order to explain the selectivity of lipase with different fatty acids.