Variation of Amino Acids in the Muscle of Crab Portunus sanguinolentus During Storage

Abstract

Amino acids are at the basis of all life processes, as they are absolutely essential for every metabolic process. In the present study variation of amino acids in the muscle of the crab Portunus sanguinolentus during frozen storage was analyzed. In the freshly caught crabs the levels of Glycine and Arginine were the highest, followed by glutamine (Gln) Ala and proline (Pro) together they accounted for 83% of the total amount of FAA. Taurine (Tau) and Glu were also in fairly large amounts. High levels of Gly, Arg, Pro, Tau and Ala are generally present in the muscle of crabs. The P. sanguinolentus muscle was also rich in Gln but low in Tau. The total amount of FAA altered slight throughout storage, but increased by 24-38% prior to the preliminary decomposition stage. The overall quantity of Arg, Gly, Ala and Glu before storage averaged 1272 mg/100 g. the total amount of these four taste-active amino acids increased by12-48% within 4 days of storage at 4°C, but hardly reduced after storage. Significant differences, except glutamic acid and tyrosine, were observed among the amino acid values changed during storage at 4°C. Major FAA such as Gly, Ala, Pro, Gln, Arg and Tau also increased, whereas, their levels usually exhibited small changes or even a decrease except that the Arg and Tau contents increased to some extent. The Glu content fluctuated during the early storage periods but its level reduced after 1 day of storage.