ATP degradation products as freshness indicator of flatfish during storage

In this study, the ATP degradation products and microbial growth during storage of flatfish were measured for assessing its freshness. LOD and LOQ of the ATP degradation products including ADP, AMP, IMP, HxR and Hx were 0.01–0.11 and 0.02–0.37 μg/g respectively, and the recovery ranged from 35.8 to 98.8%. The Hx level increased significantly during the storage period, regardless of storage temperature (p < 0.05). The initial Hx level was 245.27 μg/g, and this rapidly increased to 2563.72, 6643.69, and 4236.65 μg/g at 4, 10, and 25 °C at 14 days, 8 days, and 12 h, respectively. The correlation coefficient (R²) between microbial growth and Hx percentage ranged from 0.7709 to 0.8939. Based on the nitroblue tetrazolium colorimetric assay, the optical density of flatfish stored at 4 °C increased from 2.45 to 13.29 at 82 h of storage, which was equivalent to 442% increment.