EFFECTS OF STORAGE-TEMPERATURE ON POSTMORTEM CHANGES OF ATP AND ITS RELATED-COMPOUNDS AND FRESHNESS INDEXES IN OYSTER TISSUES

The effects of storage temperature on postmortem changes in the conten ts of ATP and its related compounds were investigated in the adductor muscle, mantle, gill, and body trunk of the oyster Crassostrea gigas i n relation to freshness. The K, K', and A.E.C. values taken for freshn ess indices were calculated from the contents of ATP and its related c ompounds. In the adductor muscle, a marked decrease in ATP was observe d together with the accumulation of AMP and IMP. The rates of ATP degr adation during storage were on the order of 0 > 10 > 5-degrees-C stora ge. AdR was detectable only in the adductor muscle. In the other three tissues the level of AMP increased along with a slow decrease in the ATP level. The accumulation of IMP was not so marked as in the adducto r muscle. The rates of ATP degradation during storage were on the orde r of 10 > 5 > O-degrees-C storage in the body trunk, and 10 > 5 is-app roximately-equal-to O-degrees-C storage in the mantle and gill. Althou gh the K value remained low during the acceptable stage in all four ti ssues, the K' value in the adductor muscle and the A.E.C. value in the other three tissues changed rapidly and continuously from the beginni ng of storage at all storage temperatures examined (0, 5, 10, 15, and 25-degrees-C). The change rates of K' and A.E.C. values were higher at higher storage temperatures. The K' value obtained on the adductor mu scle and A.E.C. values obtained on the other three tissues appeared to be useful as freshness indices for oysters.