The Exploration Of ATP Degradation Pathways In Eriocheir Sinensis And Portunus Trituberculatus And Its Quality Evaluation During Chilled Storage

Eriocheir sinensis and Portunus trituberculatus are freshwater and sea crabs with highly economic value in China. They meet the needs of vast consumers with its delicious taste and rich nutritional value. The vigor state and freshness are the most important factors to evaluate the quality of aquatic products which decides their final value. Through investigating the kinds and changes of ATP-related compounds to explore the ATP degradation pathway in two crabs meat during chilled storage, the objective is to find an effective index for evaluating the vigor state and freshness of E. sinensis and P. trituberculatus combined with the traditional quality evaluation methods which provides theoretical basis to apply in transportation, processing and preservation in the future.The method of high performance liquid chromatography(HPLC) to determinate the ATP and its related compounds was optimized. Perchloric acid as the solvent for extraction of ATP and its related compounds, when the mobile phase A: mixed phosphate(KH2PO4-K2HPO4=1:1, n/n) concentration is 0.015 mol/L and pH5.70, meanwhile the addition of methanol as the mobile phase B, 10 kinds of nucleotide related compounds were completely separated and in symmetrical shape by gradient elution program within 30 minutes. This method has a wide linear range, low detection limit, high accuracy and precision which can be applied for qualitative and quantitative analysis of 10 kinds of nucleotide related compounds in crab meat.The Optimized method of HPLC was used to determinate the contents of ATP and its related compounds in claw and body meat of E. sinensis and P. trituberculatus during chilled storage. 8 kinds of ATP-related compounds were found in two crabs, which were ATP, ADP, AMP, IMP, HxR, Hx, Xt and AdR both in two parts of two crabs meat. ATP declined continuously, and the contents of ADP, AMP, IMP and HxR raised at first then fell down. Hx and Xt were increasing continuously. A few amount of AdR were also detected during chilled storage in two crabs. The degradation pathways of two crabs were same and proposed: one was ATPâ†' ADPâ†' AMPâ†' IMPâ†' HxRâ†' Hxâ†' Xt, the other was ATPâ†' ADPâ†' AMPâ†' AdRâ†' Hx Râ†' Hxâ†' Xt. According to its pathways, K-value was revised as Ks-value, Ks=(HxR+ Hx+ Xt)/(ATP+ ADP+ AMP+ IMP+ AdR+ HxR+ Hx+ Xt)×100%.During the process from very fresh to death of the E. sinensis, sensory evaluation score decreased gradually with the time passed by, pH fluctuated in a small range in vivo and went straight up after death. The TVB-N value raised continuously both in claw and body meat. 8 kinds of ATP-related compounds were found which were ATP, ADP, AMP, IMP, Hx R, Hx, Xt and AdR. According to the detected ATP-related compounds corresponding to the E. sinensis vigor state: potential indices of ATP and Hx could be used to distinguish the live and death crabs, ATP was detected when the crab was still alive and it was death when Hx was detected; no IMP meant lively and IMP was detected with no HxR meant just still alive. However, HxR was detected with no Hx which meant the crab was dying. The V-value was established to evaluate the vigor state of the E. sinensis, when V-value was over 70% the crab was alive. 6 kinds of main free amino acid(Glycine, Alanine, Arginine, Proline, Threonine and Taurine) accounted for over 84% and 85% of the total in claw and body meat respectively during the whole storage. The Glycine in claw increased gradually and accumulated in the dying stage, then decreased after death. Glycine in body raised gradually to the peak in dying then fell down rapidly after death. The total amounts of free amino acid in two parts were crushing fall after death.During the process from very fresh to death of the P. trituberculatus, sensory evaluation score decreased gradually with the time passed by, pH fluctuated in a small range in vivo and fell down at first then increased after death. The TVB-N value raised continuously both in claw and body meat. 7 kinds of ATP-related compounds were found which were ATP, ADP, AMP, IMP, HxR, Hx and Xt. IMP, HxR and Hx could be detected meant the carb was moribund or death. When the crab was dead, the freshness was not acceptable when Ks over 30%. 6 kinds of main free amino acid(Glycine, Alanine, Arginine, Proline, Threonine and Taurine) accounted for over 83% and 90% of the total in claw and body meat respectively. The total amount of free amino acid in body meat was 1.63~2 times more than in claw, Taurine and Arginine in body were 2.47~7.13 times and 1.07~2.77 times more than in claw.