31P NMR Study of Bioenergetic Changes in Carp Muscle with Cold-CO2 Anesthesia and Non-Destructive Evaluation of Freshness

Abstract

Non-destructive phosphorus-31 nuclear magnetic resonance (31P NMR) with a surface coil attachment was used to evaluate the effects of cold-CO2 anesthesia on the energy state in carp muscle reflecting the metabolic changes of high energy phosphate compounds, inorganic phosphate (Pi), and intracellular pH (pHi). The levels of creatine phosphate (PCr), ATP, and pHi in the carp muscle were lowered by cold-CO2 anesthesia compared with those in the muscle of unanesthetized carp. The carp anesthetized with cold-CO2 seemed to be in a different metabolic state. 31P NMR with a surface coil was also used to evaluate the degree of freshness of carp muscle block stored over a 24 h period postmortem. The ratios of [PCr]/[Pi] and [ATP]/[Pi] and the pHi decreased rapidly and continuously during the acceptable stage, and were demonstrated to be potential indices to estimate the freshness of carp muscle. 31P NMR is a powerful tool for the evaluation of freshness, because of its non-invasive, convenient, rapid, and simultaneous determination of high energy phosphate compounds, Pi, and pHi in the carp muscle.