Abstract
The changes in contents of ATP and its related compounds were examined in the mantle, arm, and fin muscles of spear squid Doryteuthis bleekeri during storage at 5°C. The efficacy of the values of K, K', A. E. C., Hx ratio, Xt ratio, and Hx/AMP ratio were evaluated as freshness indices. The level of ATP at time 0 and the total content of ATP and its related compounds in the mantle muscle were higher than those in the other 2 muscles. In all muscles, ATP decreased rapidly 1 day after the beginning of storage and Hx increased markely during storage. The degradation of AMP was considered to proceed through 2 pathways, IMP and AdR pathways, in all 3 muscles. In the mantle and fin muscles, K and K' values increased markedly within 4 days of storage and may be used as freshness indicators in earlier periods of storage. The Hx, Xt, and Hx/AMP ratios increased continuously during storage; the changes in the Xt and Hx/AMP ratios were larger than those in K or K' values. It was suggested that the ratios of Hx, Xt, and Hx/AMP are more useful as freshness indices for spear squid than the K value.
