Extraction And Separation Of High-valued Components In The Euphausia Superba

Euphausia superba is a species of crustacean found in the Antarctic waters, and has been reported as one of the most abundant animal species in the word. It contains many high-valued components, such as lipids, proteins, astaxanthin and chitin. However, the development of the Euphausia superba as humans’food is limited because of the high concentrations of fluorine (F), arsenic (As) and other heavy metal elements in Euphausia superba. The common methods to extract and separate these components from the Euphausia superba are organic solvents extraction, mechanical unshelling and proteolysis. These methods can not separate different components simultaneously, and the loss ratios of the components are usually high. In addition, these methods could result in high concentrations of F, As and other harmful elements in the final products. In this paper, a novel multi-phase salting-out extraction system was developed. This study provided a simple method for the extraction and separation of lipids and other effective components from Euphausia superba and removing harmful elements from the final products.The lipids of Euphausia superba were firstly extracted by a mixed-solvent system, and a novel multi-phase salting-out extraction system (MPSOE) was then developed to extract and separate the residual lipids and other effective components from the residue of Euphausia superba. The optimal operation conditions of MPSOE were established as:the system consisted of56.5%sodium citrate/citric acid solution (sodium citrate:citric acid:water mass ratio9:1:20.5)(w/w)-18.5%ethanol (w/w)-25%hexane (w/w), krill residues quantity of7.5%(w/w), and agitation time of120min. Under these conditions, the recoveries of lipids and proteins were54.7+0.5%and58.6+1.7%, and the recoveries of astaxanthin in the top phase and the middle phase were24.1±0.6%and16.6±0.6%. The extraction efficiency of lipids in the Euphausia superba was over95%after these two extraction steps. Meanwhile, about70%of fluorine was removed from Euphausia superba, and the lipids were obtained with low concentration of fluorine, arsenic, copper and other heavy metal elements.Secondly, a series of characteristics of the lipids extracted by those two steps and the concentrations of phosphatide, free fatty acid, F, As and other harmful elements were determined by using thin layer chromatography (TCL) and gas chromatography (GC). There were some differences between those lipds from two extraction steps. The Euphausia superba lipids showed a significant effect on the inhibition of the growth of cancer cells. The IC50S of Euphausia superba lipids on HL60and U937were0.137mg/mL and0.199mg/mL, respectively. It was found that the component II whose polarity was between phosphatide and free fatty acid was the key for the inhibition on the growth of cancer cells.Thirdly, proteolysis was used to separate proteins and chitin from the solid layer after the MPSOE. The trypsin was selected as the best protease after the single factor experiments and the orthogonal experiments. The optimal operation conditions of proteolysis were established as:the concentration of added trypsin of2%, the pH of8, the temperature and time of35℃and10h. Under these conditions, the degree of hydrohysis and the reduction of the residue were44.9%and76.8%.