Extraction Of Oils From Antarctic Krill(Euphausia Superba)

Due to huge biomass and rich nutrition,Antarctic krill(Euphausia superba)has attracted increasing attention in recent years.Krill oil is a rich source of phospholipid polyunsaturated fatty acids(PUFA).It has ability of antiinflammation,antioxidation,antihyperlipidaemia effect,antihyperglycaemic effect and cardioprotective effect.Therefore,it possesses high developing and utilizing value.In this study,solvent extraction method was used to prepare krill oil.The characteristic values of oils extracted by different solvents and from different materials were determined to evaluate the quality of them.The present research provides basic information for industrialization extraction of krill oil.In this study,solvents including n-hexane,alcohol,acetone,a mixed solution of n-hexane and alcohol(2:1)and a mixed solution of acetone and alcohol,as well as alcohol and acetone consecutive extraction were used to extract krill oil from heat drying krill powder.The recovery yield of raw krill oil was 64.28%,88.83%,63.60%,100.68%,106.66%and 103.86%.The krill oil extract by alcohol and acetone consecutive extraction has the highest content of phospholipid and protein,with values of 53.40%and 21.22%,respectively.By contrast,the oil extracted by acetone has the lowest content of phospholipid and protein,with values of 26.44%and 5.04%,respectively.The krill oil extract by n-hexane has the highest peroxide value,with value of 1.39 mmol/kg.By contrast,the oil extracted by acetone has the lowest peroxide value,with value of 0.68 mmol/kg.The krill oil extract by alcohol and acetone consecutive extraction has the highest acid value,with value of 41.27 mg/g.By contrast,the oil extracted by n-hexane has the lowest acid value,with value of 7.11mg/g.The krill oil extract by alcohol and acetone consecutive extraction has the highest PUFA content,with value of 40.24%,including 22.71%of EPA and 10.30%of DHA.By contrast,the oil extracted by acetone has the lowest PUFA content,with value of 22.23%,including 10.60%of EPA and 3.52%of DHA.When the mixed slolution of n-hexane and alcohol(2:1)was used to extract drying krill powder,the raw oil has relatively better quality with phospholipid content of 39.16%,protein content of 7.93%,acid value of 13.33 mg/g,peroxide value of 0.75 mmol/kg.Meanhwhile,PUFA accounts for 35.26%of total fatty acids,including 18.28%of EPA and 10.18%of DHA.Krill oils were extracted from heat drying krill powder,freeze-dried krill shell powder,freeze-dried krill powder and krill meat powder by using n-hexane,alcohol and a mixed solution of n-hexane and alcohol(2:1).The phospholipid content,protein content and fatty acid composition of the krill oils extracted by same solvent from different materials were slightly different.The krill oil extract from heat drying krill powder have the highest peroxide value,by contrast,the oils extracted from other three kinds of raw materials have approximate peroxide values.The krill oil extract from freeze-dried krill powder has the highest acid value,by contrast,the oil extracted from drying krill powder has the lowest acid value.Heat drying krill powder and krill meat powder were mixed with corn flour and potato starch respectively,and then granulated with extrusion.The add ratio of the accessory range from 0 to 20%.The optimum mixture ratio was 80:20 for heat drying krill powder and corn flour,85:15 for heat drying krill powder and potato starch,and 85:15 for krill meat powder and potato starch.Under the above conditions,the particles were uniform and complete.Meanwhile,the recovery yields of crude krill oil for the particles were higher than that of raw krill powder.This suggests that the granulation with extrusion is conducive to oil extraction.