Storage of Yellowtail ( Seriola quinqueradiata ) White and Dark Muscles in Ice: Changes in Content of Adenine Nucleotides and Related Compounds

Adenine nucleotides and their related compounds in white and dark muscles of yellowtail Seriola quinqueradiata were measured and compared during ice storage. In white muscle, adenosine 5′‐triphosphate was degraded rapidly to inosine 5′‐monophosphate, which then underwent gradual build‐up of inosine (HxR). In dark muscle, HxR accumulated very rapidly and the K value, a freshness index, thus increased at a greater initial rate than in the white muscle (62 vs 3%/day). Urate occurred in a small amount only in the white muscle stored for over 40 days (0.2 μmole/g), while little was found in the dark muscle during the entire storage period. Nicotinamide adenine dinucleotide, which existed in both the fresh white and dark muscles (0.8 vs 0.4 μmole/g), decreased rapidly in the early stage of storage.