Field gradient CPMG applied on postmortem muscles.

As a new approach, Carr-Purcell-Meiboom-Gill (CPMG) experiments were performed in vitro on porcine muscles (n = 10) during the period from 15 min to 85 min postmortem and again at 24 h postmortem in the absence (G = 0) and the presence of an external field gradient (G = 0.5*10(-3) T/m), which was applied throughout the CPMG sequence. The experiments were performed on low-field nuclear magnetic resonance (NMR) equipment (0.47 T). Due to the inclusion of different pre-slaughter treatments (adrenaline treatment and pre-slaughter exercise/electrical stunning), the muscles could be divided into (I) a group (n = 5) characterized by a reduced decrease in pH postmortem and a high water-holding capacity and (II) a group (n = 5) characterized by an increased rate of pH decrease postmortem and a low water-holding capacity. Distributed analysis of the CPMG data revealed two major relaxation populations with relaxation times about 30-40 and 200-500 ms, respectively, and comparison of data obtained with G = 0 and G = 0.5*10(-3) T/m revealed effects of the external gradient on the relaxation time of both the two relaxation populations, which implies that both diffusion and relaxation contributes to the relaxation of the two populations. At 24 h postmortem the effect of the external field gradient on the relaxation time was significantly affected by muscle group (I vs. II), which reveals local differences in water diffusion in the two meat qualities. Finally, the discriminatory power with regard to muscle group (I vs. II) was investigated for data acquired with G = 0 and G = F = 0.5*10(-3) T/m, and both the two types of data were found highly suitable for separation of muscles according to meat quality.

[1]  P. Basser,et al.  Estimation of the effective self-diffusion tensor from the NMR spin echo. , 1994, Journal of magnetic resonance. Series B.

[2]  S B Engelsen,et al.  Prediction of water-holding capacity and composition of porcine meat by comparative spectroscopy. , 2000, Meat science.

[3]  W. Derbyshire,et al.  An NMR investigation of rigor in porcine muscle. , 1974, Biochimica et biophysica acta.

[4]  H. J. Andersen,et al.  Continuous distribution analysis of T(2) relaxation in meat-an approach in the determination of water-holding capacity. , 2002, Meat science.

[5]  J. E. Tanner,et al.  Self diffusion of water in frog muscle. , 1979, Biophysical journal.

[6]  R. Lawrie,et al.  The effect of pre-treatment with various drugs on post-mortem glycolysis and the onset of rigor mortis in rabbit skeletal muscle. , 1962, Journal of comparative pathology.

[7]  H. J. Andersen,et al.  The significance of cooling rate on water dynamics in porcine muscle from heterozygote carriers and non-carriers of the halothane gene-a low-field NMR relaxation study. , 2003, Meat science.

[8]  J R Hansen,et al.  Pulsed NMR study of water mobility in muscle and brain tissue. , 1971, Biochimica et biophysica acta.

[9]  H. J. Andersen,et al.  Origin of multiexponential T(2) relaxation in muscle myowater. , 2001, Journal of agricultural and food chemistry.

[10]  K. Honikel,et al.  Reference methods for the assessment of physical characteristics of meat. , 1998, Meat science.

[11]  V J Napadow,et al.  Quantitative analysis of three-dimensional-resolved fiber architecture in heterogeneous skeletal muscle tissue using nmr and optical imaging methods. , 2001, Biophysical journal.

[12]  F. Capozzi,et al.  Relationships between (1)H NMR relaxation data and some technological parameters of meat: a chemometric approach. , 2000, Journal of magnetic resonance.

[13]  B. Hills,et al.  Combined relaxation and diffusion studies of porous media using the multigrade CPMG sequence. , 1996, Magnetic resonance imaging.

[14]  K. Brownstein,et al.  Importance of classical diffusion in NMR studies of water in biological cells , 1979 .

[15]  J F Harmon,et al.  Pulsed NMR measurements of the diffusion constant of water in muscle. , 1971, Archives of biochemistry and biophysics.

[16]  J. Renou,et al.  Nuclear magnetic resonance measurements on pork of various qualities. , 1985, Meat science.

[17]  C F Hazlewood,et al.  Nuclear magnetic resonance measurement of skeletal muscle: anisotrophy of the diffusion coefficient of the intracellular water. , 1976, Biophysical journal.

[18]  Søren Balling Engelsen,et al.  Pre-rigor conditions in beef under varying temperature- and pH-falls studied with rigometer, NMR and NIR , 2000 .

[19]  L. Hedlund,et al.  Pre‐ and postmortem diffusion coefficients in rat neural and muscle tissues , 1991, Magnetic resonance in medicine.

[20]  M. Ruusunen,et al.  Pork Quality: Genetic and Metabolic Factors. , 1993 .

[21]  Dynamic NMR Q-space studies of microstructure with the multigrade CPMG sequence. , 1996, Magnetic resonance imaging.

[22]  K. Nicolay,et al.  Single‐shot diffusion trace 1H NMR spectroscopy , 2001, Magnetic resonance in medicine.

[23]  H. J. Andersen,et al.  Comparative study of low-field NMR relaxation measurements and two traditional methods in the determination of water holding capacity of pork. , 2001, Meat Science.

[24]  Jean-Marie Bonny,et al.  Water diffusion features as indicators of muscle structure ex vivo. , 2002, Magnetic resonance imaging.

[25]  Hans Busk,et al.  Changes in orcine muscle water characteristics during growth--an in vitro low-field NMR relaxation study. , 2002, Journal of magnetic resonance.

[26]  H. J. Andersen,et al.  pH Dependence of the Progression in NMR T2 Relaxation Times in Post-mortem Muscle , 2003 .

[27]  H. J. Andersen,et al.  Physical changes of significance for early post mortem water distribution in porcine M. longissimus. , 2004, Meat science.

[28]  Hanne Christine Bertram,et al.  Relationship between meat structure, water mobility, and distribution: a low-field nuclear magnetic resonance study. , 2002, Journal of agricultural and food chemistry.

[29]  A. Karlsson,et al.  Control of post mortem pH decrease in pig muscles: experimental design and testing of animal models. , 2000, Meat science.

[30]  A. Leroy-Willig,et al.  Simultaneous measurements of diffusion and transverse relaxation in exercising skeletal muscle. , 1995, Magnetic resonance imaging.

[31]  H. J. Andersen,et al.  Factors of significance for pork quality-a review. , 2003, Meat science.