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Degradación postmorten en músculo de conejo: evolución de la microestructura

1999; EDITIONS PUBLICATIONS ALIMENTARIAS SA; Issue: 308 Linguagem: Inglês

0300-5755

María Angeles Lluch Rodríguez, I. Hernando, Indira Sotelo, I. Pérez Murena,

Rabbits: Nutrition, Reproduction, Health

The objective of the present paper is the study of the evolution postmortem of the muscle semimembranosus of rabbit during the first 72 hours in refrigerated storage, by Scanning Electron Microscopy (SEM and Cryo-SEM); and the muscular pH is too analysed during this period. This muscle presents 71% of humidity, and the pH decreases from 6.68 until 5.91 the first 10 h postmortem, and decreases lightly to 5.97 at 72 h postmortem. After 1 h postmortem, this muscle observed by Cryo-SEM appears lengthened and intimately linked constituting bundles, with the typical Z-disk structure in the surface of fibres. The fibres are interconnected and perfectly adhered by the endomisium, associated in bundles separated for the perymisium; and surrounded by the epymisium. Inside of the fibres, the myofibrils are intimately linked each other and with the sarcolemma, constituting a compact structure in which some mitochondrion can be observed. Intermyofibrilar connections which also link myofibrils to the sarcolemma can be observed, they could be proteins described by some authors in other types of meat like constituents of a cytoskeletal network (costameres). This network extends inside the muscle cell encircling myofibrils at the Z-disk and runs from myofibril to myofibril to link adjacent Z-disks laterally and they link myofibrils to the sarcolemma too. After 72 h at refrigerated storage, muscular fibres are degraded and not clearly individuals like the first day postmortem; although most Z-disks remain almost unchanged structurally. The intermyofibrillar connections and the connections between myofibrils and sarcolemma appear broken, some fractured myofibrils can also be observed inside the cell, and the connective tissue appears like a more lax structure if it is compared with the muscle of rabbit recently sacrificed. SEM observations confirm the results described in this paper by Cryo-SEM. Finally, authors could say that the structural changes observed are coincidental with the evolution of the pH, and actually they have evidences that a protein degradation is also produced, refered to the increase of N-soluble.