Post-mortem biochemical changes in the muscle of Japanese spiny lobster during storage

The changes in content of ATP and its related compounds, and free amino acids were examined in the muscle of Japanese spiny lobster Panulirus japonicus during storage at 0, 5, and 20 degrees C in relation to freshness and decomposition. The level of ATP immediately after death was 8.6 mu mol/g and decreased during storage. AMP increased slowly and accumulated. IMP, inosine and hypoxanthine, which were not detected immediately after death, increased during storage. K values ranged from 20 to 25% at the stage of initial decomposition. Main free amino acids were taurine, glutamic acid, proline, glycine and arginine. Sweet and ''umami'' tasting active amino acids were abundant in the muscle of Japanese spiny lobster. Alanine increased during storage and reached 165 to 181 mg/100 g at the stage of initial decomposition. Ornithine increased gradually at the acceptable stage and was produced remarkably at the stage of initial decomposition. On the contrary, degradation of arginine was observed. It was concluded that the K value and ornithine were useful as potential indices for freshness and decomposition of Japanese spiny lobster.