Mitochondrial oxygen consumption in permeabilized fibers and its link to colour changes in bovine M. semimembranosus muscle

Animal and muscle characteristics were recorded for 41 cattle. The oxygen consumption rate (OCR) of M. semimembranosus was measured between 3.0-6.4 h post mortem (PM3-6) and after 3 weeks in a vacuum pack at 4 °C. Colour change measurements were performed following the 3 weeks using reflectance spectra (400-1100 nm) and the colour coordinates L*, a* and b*, with the samples being packaged in oxygen permeable film and stored at 4 °C for 167 h.Significant individual animal differences in OCR at PM3-6 were found for mitochondrial complexes I and II. OCR of complex I declined with increased temperature and time PM, while residual oxygen-consuming side-reactions (ROX) did not. OCR of stored muscles was dominated by complex II respiration. A three-way regression between samples, colour variables collected upon air exposure and OCR of 3 weeks old fibres revealed a positive relationship between OCR and complex II activity and also between OCR and OCRROX. The presence of complex I and β-oxidation activities increased metmyoglobin formation.