Nutritional Value and Amino Acids in Tuna Steam-cooking Liquid

  Objective  Nutritional value and amino acids (AAs) in tuna steam-cooking liquid were analyzed.

  Methods   The tuna processing liquid was collected for chemical determinations by liquid chromatography-mass spectrometry and an amino acid analyzer.

  Results  The solids in the liquid contained 76% protein which was 83.26% acid soluble peptides of less than 1,000 Da in molecular weight. The essential amino acid index of the liquid was 20.64 with a biological value of 10.80. Of the total AAs, 17.86% were free AAs; 19.63%, ACE-inhibiting; 9.71%, anti-xanthine oxidase; 27.27%, bone cell proliferation-promoting; and 7.16 %, hydroxyproline (which was 3.29% of the total protein with 63.83 % in the form of peptides). The bone cell proliferation promotion function was closely related to the protein concentration of the liquid.

  Conclusion   The protein in the tuna steam-cooking liquid was mainly small molecule peptides derived from collagen.