Study On Extraction, Refine And Enrichment Of PUPA Of Oil From Euphausia Superba

The nutritional value of Antarctic krill (Euphausia superba) is high, the quantity is largeIt is the key of the resource development at home and abroad. Its body oil is rich in lecithinand polyunsaturated fatty acids, which accounted for4.40%of the wet weight. In recent years,China’s Antarctic krill catch keeps increasing, but the utilization rate is low, mainly used infishery breeding. This paper mainly studies the following aspects.Firstly, the organic solvent method for krill extraction is studied. Results show that thebest conditions for the process is the volume ratio of ethanol and hexane of3:2(v/v)，thesolid-liquid ratio of krill and solvent of1:6, the temperature of50℃, extracting time of80min. The yield of the Antarctic oil is80.25%.Secondly, the process of extraction shrimp oil by enzymatic hydrolysis method is studied.The optimum process conditions of enzymatic hydrolysis: adding neutral protease and thenadd the alkaline protease, liquid ratio of1:4, the best condition of neutral protease is45℃,pH7, adding amount of0.125%(w/w), time of2.5h, the best condition of Alkaline protease is50℃, pH8, adding amount of0.1%(w/w), for2h.This paper combines adjust pH and freezethawing and centrifugal method for demulsification, mainly discussed the pH and centrifugaltwo factors. The best process conditions: enzymolysis liquid transfers to pH5first, add-20℃, frozen in the refrigerator for24h, around35℃to thaw for30min, and then4000rpm centrifugal20min. The best process conditions of liquid-liquid extraction: ethanol andn-hexane volume mixing ratio of3:7, and solid-liquid ratio1:5, the time of120min, thetemperature of50℃, the stirring speed of150rpm. Enzymatic hydrolysis of shrimp oilextraction rate reachs73.42%.Thirdly, refine the crude oil obtained by organic solvent extraction and enzymatichydrolysis extraction, including degumming, deacidifying and decolorating. The bestconditions for refining the crude oil obtained by solvent extraction: in degumming processwater content is2%(w/w), in deacidifying process the concentration of NaOH is11%, indecoloring activated carbon agent is6%(w/w). Finally the refined oil is the peroxide value of5.05meq/kg, acid value of1.94mgKOH/g. The best conditions for refining the crude oilobtained by enzymatic hydrolysis extraction: in degumming process water content is3%, indeacidifying process the concentration of NaOH is14%, in decoloring activated carbon agentis6%. Finally the refined oil is the peroxide value of3.52meq/kg, acid value of2.06mgKOH/g.Fourthly, analyse of the components, physical and chemical indicators and fatty acidcomposition of the Antarctic krill oil. Found through the analysis of the oil components, theenzymatic hydrolysis of phospholipids and glycolipids content in crude oil is higher than organic solvent extraction of crude oil. Comparative analysis physicochemical indexes of thecrude oil obtained by enzymatic hydrolysis, organic solvent extraction,Soxhlet extraction andFolch method, the refined oil obtained by enzymatic hydrolysis and organic solvent extraction.The results show that, the peroxide value of the crude oil obtained by enzymatic hydrolysis isthe lowest, but the highest acid value. Iodine value and saponification value are higher thanorganic solvent, slightly lower than Folch method. Moisture and volatile matter and thecontent of insoluble impurities reach the secondary index of crude fish oil. This showsenzymatic hydrolysis is superior to other methods in terms of preventing fatty acid oxidation,but because of the enzymatic hydrolysis in the water system the acid value is higher. Therefined krill oil can be reached the standard of secondary refining oil, so the krill oil obtain bythe two methods can be further processed for quality products. In the analysis of fatty acids,23kinds of fatty acids are detected.The unsaturated fatty acid content of the crude oilobtained by enzymatic hydrolysis reachs68.93%, significantly higher than organic solventcrude oil (51.29%). EPA and DHA content reached21.84%and9.54%, significantly betterthan either organic solvent crude oil (EPA13.58%, DHA5.63%). After refining the fatty acidcomposition and content in the two methods is to close.Finally, urea adduction fractionation is studied in the oil for enrichment of unsaturatedfatty acids, including saponification, decoloring and inclusion of three parts. The bestcondition of saponification: add alkaline=krill oil quality*saponification value*1.1,ethanol and water volume ratio of6:1, saponification temperature50℃, saponification time60min. The best condition of decoloration: activated carbon addition amount of2g/L, about10min in25℃or so. The best condition of urea inclusion: quality of urea and fatty acidsratio3:1, crystallization temperature0℃and20h crystallization time. After urea inclusionof DHA and EPA reachs63.75%, the purity of the EPA’s yield is89.59%, the yield is94.69%of DHA.