Preparation And Separation Of Fatty Acid Ethyl Esters From Fish Oil

ω-3unsaturated fatty acids have become hot spot in the purification of naturalproduct and medicine research due to the special physiology functions.Eicosapentaenoic acid (EPA), one of the most imoportant ω-3unsaturated fatty acids,has the effect such as reducing blood-lipid, preventing and curing heart diseases andso on. Currently, fish oil is the main commercial source of EPA, fish oil capsulesriched in EPA and pharmaceutical preparations are widely used. In this paper, fish oilglycerides as the raw material were turned into fatty acid ethyl esters (FAEE). Themethod of high vacuum distillation was proposed to separate EPA ethyl ester(EPA-EE). The research will provide a new thought for the separation and purificationof unsaturated fatty acids.The content of fish oil raw material was determined by GC and GC-MS. Thephysicochemical properties such as acid value、iodine value、 saponification valuewere analyzed to provide reference for the production of FAEE.Considering the physicochemical properties, a two-step process was chosen toproduce FAEE by comparing with other methods. First step was pre-esterificationcatalyzed by concentrated sulfuric acid in order to reduce the acid value, followed bytransesterification catalyzed by KOH to produce FAEE. The optimal conditions ofpre-esterification and transesterification were determined by orthogonal design,regarding acid value and yield of FAEE as target respectively. For thepre-esterification process, when temperature was70℃，the concentration of sulfuricacid was1.5%of fish oil, reaction time was1h, the lowest acid value was0.87mgKOH/g. For the transesterification process, when temperature was70℃，theconcentration of KOH was0.5%of fish oil, reaction time was0.5h, the highest yieldof FAEE was92.5%.The EPA-EE was separated from fish oil FAEE by high vacuum batch distillation.The fraction was collected of which EPA-EE content was85.2%and the recovery wasabout54%. The second distillation was carried out using FAEE of which EPA-EEcontent was over70%as raw material, the purity of EPA-EE was over92%, therecovery was about48%. AgNO3-silica gel column chromatography was used forfurther purification of EPA ethyl ester, the content of which was increased to over97%.The high vacuum batch distillation process was simulated by Aspen Plus. The properties of the FAEE lacking in database were also estimated by the software.One-column and two-column continuous distillation process simulation were alsoestablished. The appropriate conditions of two-column distillation were determined bysensitivity analysis. For both columns, the stage number was set to16. For the columnB1, the mole reflux ratio was4, D/F was0.05, and the feed stage was5. For thecolumn B2, the mole reflux ratio was6, D/F was0.28, and the feed stage was13.Under above-mentioned conditions, the purity of EPA-EE can reach94.8%.