| 1. |
- Lundberg, Peter, et al.
(författare)
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NMR as a Noninvasive Tool in Meat Research
- 1987
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Ingår i: Annals of the New York Academy of Sciences. - : John Wiley & Sons. - 0077-8923 .- 1749-6632. ; 508, s. 516-522
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Tidskriftsartikel (refereegranskat)abstract
- NMR has been used for some time for in vivo measurements of biological tissues and has established itself as a valuable and complementary method to be used in parallel with traditional extraction methods. To date most attention has been paid to problems such as central biochemical pathways, energy metabolism in simple organisms and organs, and of course to problems encountered in medicine. There has been relative little interest in applying NMR to problems in food technology, even if these questions can have a tremendous impact on everyday life. Following a suggestion by Gadian,' we show here that multinuclear metabolic NMR is a useful method for studying post-mortem events in carcasses of slaughtered animals.The treatment and storage of carcasses during the first hours after slaughter is of extreme importance for the final quality and tenderness of the meat. Mistreatment can cause large economical losses and waste of valuable food. For example, in order to reduce the risk of bacterial infections one would like to cool down a carcass as soon as possible. Nevertheless, if a muscle is cooled down below 15OC before the postmortem metabolism is completed it may shorten dramatically thus decreasing the tenderness of the meat.' Therefore it is important to measure the rates of postmortem metabolism and to study the efficiency of methods that are aimed at speeding up this process.
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| 2. |
- Lundberg, Peter, et al.
(författare)
-
Post-mortem metabolism in fresh porcine, ovine and frozen bovine muscle
- 1987
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Ingår i: Meat Science. - : Elsevier. - 0309-1740 .- 1873-4138. ; 19:1, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- Post-mortem metabolism was followed by phosphorus-31-NMR in muscle samples obtained from freshly slaughtered pigs and lambs. Resonances for creatine phosphate (CP), ATP, inorganic phosphate (Pi) and sugar phosphates (SP) could be discerned and the intracellular pH could be determined from the spectra. The rates of post-mortem metabolism varied in the following fashion: porcine muscle > ovine muscle > bovine muscle. However, the course of post-mortem metabolism was, in all cases, the same. CP disappeared first and then ATP. Simultaneously, Pi increased, while SP remained relatively constant. The intracellular pH decreased to pH 5·5 in all tissues.In a separate set of experiments the post-mortem metabolism during thawing was studied in bovine muscles that had been frozen immediately after slaughter. Again, the same course of post-mortem metabolism was observed, but the thaw shortening was accompanied by an extremely rapid post-mortem metabolism, which was more than ten times as fast as that measured for fresh bovine muscles. The intracellular pH decreased from 7·2 to 5·5 in 45 min. This rapid metabolism started only after the sample ha reached 0°C. Resonances for metabolites were broadened in frozen muscles due to the limited motions that are allowed within the ice lattice.
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