Prieto, N., López-Campos, Ó., Zijlstra, R. T., Uttaro, B. and Aalhus J. L. 2014. Discrimination of beef dark cutters using visible and near infrared reflectance spectroscopy. Can. J. Anim. Sci. 94: 445-454. This study examined the potential of visible and near infrared reflectance spectroscopy (Vis-NIRS) to segregate dark cutters from normal beef. One hundred and twenty beef carcass sides were selected from a slaughter plant by experienced graders according to their carcass grade: 60 A grade carcasses (normal) and 60 B4 grade carcasses (dark cutters). At approximately 48 h post mortem, a 2.5-cm-thick steak (at ~7/8th thoracic vertebrae) was removed, vacuum packaged and frozen at -25°C until spectra collection. Four Vis-NIRS analyses were performed with different instruments and sample presentation. Partial least squares discriminant analysis based on Vis-NIR spectra correctly classified 95% of the intact non-oxygenated beef samples from both A and B4 grade carcasses using a portable LabSpec^®4 spectrometer, and 88 and 93% of the intact beef samples from A and B4 grade carcasses, respectively after 20 min of exposure to atmospheric oxygen. When a bench top NIRSystems 6500 monochromator was used, 90% of the bloomed intact beef samples were correctly assigned to both A and B4 grading categories, and 90 and 91%, respectively, of the bloomed homogenized samples. Further work remains to be carried out to develop robust Vis-NIRS models to be implemented on-line in the abattoir, where portable equipment applied directly on the carcass could objectively assist in dark-cutting carcass segregation.