1Hokkaido Industrial Technology Center, Hakodate, Hokkaido 041-0801, 2Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido 041-8611, 3Department of Biochemistry, Asahikawa Medical College, Asahikawa, Hokkaido 078-8510, Japan
Changes in the contents of ATP related compounds in the gonad of sea urchin Strongylocentrotus nudus stored in artificial seawater were investigated. A gradual decrease of ATP content was followed by an accumulation of HxR and Hx during storage, while total nucleotide content decreased from 2.6 to 1.2 μmol/g in 8 days indicating a leaking of the compounds from the gonad. The ATP content relative to the sum of ATP related compounds was used to show the ATP content of the gonad. Turbidity of seawater used for storage, a commercial sensory freshness index of gonad of sea urchin, also increased during storage. The increase in turbidity seemed to correspond to the decrease in relative ATP content. The effect of oxygen volume filled in the storage bag on the change in the relative ATP content of gonad and on the turbidity increase of seawater was studied. Decrease in the relative ATP content and turbidity development were both suppressed by an increase in filled oxygen volume. Almost no increase in the marine bacteria population was observed during the storage under any conditions. It was concluded that storage of sea urchin gonad in oxygenated sea water was an effective method for main taining freshness.