Changes in Early Postmortem Contents of ATP and Other Nucleotides in Normal and Poor Quality-simulated Pork

Abstract

Early postmortem ATP level is known as a good predictor of pork quality. Pork carcasses were divided into two; one was electrically stimulated (ES) to simulate poor quality pork and the other was left untreated and served as a control normal pork. Fractions of longissimus were excised from carcasses regularly for 2 hours after death and deep-frozen (-80 o C) until analyses. The ATP level of normal untreated control pork decreased from 5.00 to 2.04 μmole/g within 2 hours postmortem. The decrement of ATP was approximately 60% of its initial content. In the meantime, ES poor quality pork had a more drastic rate of ATP decrease. Electrical stimulation itself decreased ATP level from 4.70 to 3.50 μmole/g, by approximately 25%. ATP level of ES pork dropped to 1.71 μmole/g within 1 hour postmortem and was further plunged to 0.26 μmole/g and almost exhausted during the next hour. The level of IMP increased from 0.49 to 3.17 μmole/g and it became the dominant nucleotide within 2 hours postmortem. Electrical stimulation prompted the increase of IMP from 0.69 to 3.19 μmole/g and its level went up to 6.64 μmole/g within 2 hours postmortem. The level of ADP also decreased from 1.45 to 0.67 μmole/g for 2 hours after death and ES also accelerated ADP breakdown. The AMP levels were lower than those of other nucleotides and increased from 0.16 to 0.31 μmole/g within 2 hours postmortem. The increase of AMP was accelerated between 60 and 90 minutes after electrical stimulation. Early postmortem electrical stimulation prompted a drastic rate of changes in contents of 4 nucleotides during 2 hours postmortem. In the meantime, the ATP levels for ES poor quality pork were much lower than those of normal pork.