Evaluation of Nutritive Value of Protein in Different Antarctic Krill(Euphausia superba)Products

The basic components,protein composition and distribution state,amino acid composition were measured. SDS-PAGE,microscopic observation,and infrared spectroscopy were used to analyze the protein in krill meat. Krill surimi,ordinary krill powder,skim krill powder and defluorination krill powder prepared from Antarctic krill as raw materials were analyzed. The results showed that the protein of ordinary krill powder in these five kinds of Antarctic krill products had the lowest protein content(65.12%),but still exceeded the fish meal of the special grade(GB/T 19164-2003,protein content>65%)the nutritive value of its protein was analyzed according to the amino acid model proposed by FAO/WHO,the essential amino acids content,the essential amino acids(EAA)to nonessential amino acids(NEAA)ratios and nutrition index(NI)of protein in these five kinds of Antarctic krill products were higher than 47.835%(>47.548% of casein),91.571%,56.432%,respectively. The ratio of essential amino acids of protein in the five Antarctic krill products was appropriate,and the essential amino acid index(EAAI)was also superior to 75.627 of casein. Due to thermal processing,ethanol degreasing,and acid treatment deamidation,the high molecular weight protein in the krill product was degraded,and the low molecular weight protein was increased,in addition,the ratio of a-helix to β-sheet in the krill products protein decreased from 1.222 to 0.835,and the the content of β-turn angle also decreased from 31.39% to 26.37%. By studying the nutritive value of protein in different Antarctic krill products,it was demonstrated that the Antarctic krill products can serve as a good source of protein.