Euphausia, a kind of mysis, is known as a feed stuff of aquatic animal and cetacean; the nutritive constituents of the Euphausia are being watched with interest from the biochemical as well as technological points of view. In the present experiments, the protein and nonprotein nitrogenous constituents of the Euphausia, E. pacifica, E. superba and E. vallentini, have been analysed by the automatic amino acid analyser or by the individual chemical methods.
The chemical compositions of fresh samples are given in Table 1, and the amounts of crude protein were around 17%. The pattern of amino acids in hydrolysates of protein given in the Table 2 was similar to that of muscle protein of common crustacean reported by the other authors, but somewhat higher content of tryptophan in the present samples are of interest from the nutritional viewpoint.
The amount of extractive nitrogen of E. pacifica (whole) was higher than that of E. superba (muscle), and the concentrations of peptide-composing amino acids, free amino acids and their related compounds of these two are tabulated in Table 3. Relatively large amounts of alanine, glycine, proline, arginine, taurine, trimethylamine oxide and betaine were found, and the calculations of nitrogen summarized in the table show that 94 and 96% of extractive nitrogen are respectively accounted for.