Estimating postmortem interval by bioluminescent determination of atp content in the muscle of olive flounder (Paralichthys olivaceus)

Abstract

This study was carried out to determine ATP in the muscle in olive flounder (Paralichthys olivaceus) content by using a luminometer, with the aim to facilitate field estimation of the postmortem interval of sliced raw fish, and establishing the extractant and extraction method to measure ATP content in fish muscle with a luminometer. In consideration of low variations in measurements and fewer dilutions, 0.5 M phosphate buffer (pH 6.8) was selected as the optimal extraction buffer for this method. As a proxy for ATP content, measurements from the luminometer in relative light units (RLU) in olive flounder muscle stored at 58C resulted in 1,594 3 103 to 2,154 3 103 RLU from the fish muscle at 0 h postmortem, 922 3 103 to 1,616 3 103 RLU at 10 h postmortem, and 6.3 3 103 to 7.2 3 103 RLU at 24 h postmortem. Thus, increasing the time in storage reduced RLU values, and the ATP content rapidly declined after 24 h postmortem. ATP content measured by high-performance liquid chromatography (HPLC) ranged from 7.86 to 8.9 μmol/g and had almost disappeared after 24 h postmortem. The comparison between luminometer-measured RLU and HPLC-based ATP content showed a high correlation of r2 ¼ 0.98 (600 g of fish), 0.96 (800 g), 0.97 (1,000 g), and 0.97 (1,200 g). Therefore, a luminometer can provide rapid and accurate field determination of the postmortem interval of sliced raw fish within 24 h.