Chemical Indices for Assessing Freshness of Shellfish during Storage

The changes in content of ATP and related compounds were investigated in the muscle of oyster, hard clam, ark-shell, and abalone during storage at 5°C. We evaluated the efficacy of the K, K', and A. E. C. values calculated from the content of ATP and related compounds as freshness indices. The degradation patterns of ATP and related compounds were different among the 4 species. ATP decreased rapidly in the oyster and hard clam, but gradually in the ark-shell and abalone. AMP accumulated in all 4 species, while further degradation to IMP and/or HxR occurred markedly in the oyster and ark-shell. Although the K values on the hard clam, ark-shell, and abalone were low at the acceptable stage, the K' value on the hard clam increased slowly but linearly and increased rapidly and linearly for the oyster and ark-shell from the beginning of storage. For the ark-shell and abalone, the A. E. C. value decreased rapidly and linearly during the acceptable stage. The K' and A. E. C. values appeared to be useful as freshness indices for shellfishes.