Decomposition of ATP is one of the major biochemical postmorten changes in muscles of fish and shellfish. During this process, ATP, ADP, and AMP decompose quickly to form and build-up inosine and hypoxanthine. The increase in the ratio of inosine and hypoxanthine to the total quantity of ATP and its related substances corresponds to the decline of the fish’s freshness well. This ratio is called K value and used as an index to represent the freshness of fish flesh.

Sample : ATP, ADP, AMP, IMP, Hypoxanthine, Inosine