Post-mortem changes in porcine M. longissimus studied by solid-state C-13 cross-polarization magic-angle spinning nuclear magnetic resonance spectroscopy

Abstract

Solid-state C-13 cross-polarization (CP) magic-angle spinning (MAS) nuclear magnetic resonance (NMR) experiments are carried out for the first time on rapidly frozen muscle biopsies taken in M. longissimus in vivo and at 1 min, 45 min, and 24 h post-mortem from three pigs. Two of the pigs were CO2-stunned (control animals), and one was pre-slaughter-stressed (treadmill exercise) followed by electrical stunning to induce difference in metabolism post-mortem. C-13 resonance signals from saturated and unsaturated carbons in fatty acids, carboxylic carbons, and carbons in lactate and glycogen are identified in the solid-state NMR spectra. The C-13 CP MAS spectra obtained for postmortem samples of the stressed, electrically stunned pig differ significantly from the post-mortem control samples, as the intensity of a resonance line appearing at 30 ppm, assigned to carbons of the methylene chains, is reduced for the stressed pig. This spectral difference is probably due to changes in lipid mobility and indicates altered membrane properties in the muscle of the stressed/electrically stunned animal when compared with the control animals already 1 min post-mortem. In addition, the post-mortem period changes in glycogen carbons can be estimated from the C-13 CP MAS spectra, yielding a correlation of r = 0.74 to subsequent biochemical determination of the glycogen content.

Keywords

glycogen; muscle biopsies; C-13 MAS NMR spectroscopy; membranes; lactate

Published in

Journal of Agricultural and Food Chemistry
2003, Volume: 51, number: 7, pages: 2064-2069 Publisher: AMER CHEMICAL SOC

UKÄ Subject classification

Food Science


Publication identifier

DOI: https://doi.org/10.1021/jf020919x

Permanent link to this page (URI)

https://res.slu.se/id/publ/85676