Beef colour evolution as a function of ultimate pH.

Colour in CIELAB space was assessed in 31 yearling entire male cattle from their reflectance spectra (400-700 nm) at six different times (0 min, 15 min, 5 h, 48 h, 6 days and 9 days). Cluster analysis applied to all the colour co-ordinates divided the samples into two groups according to their ultimate pH (pHu): pH<6.1 and pH⩾6.1. pH ranged between 5.17 and 7.10. Colour development in pH⩾6.1 group was less visually appreciable than in pH<6.1 group. This difference was also observed in the reflectance spectra. The application of discriminant analysis to these groups established that b* and h* CIELAB co-ordinates are the most discriminant variables. Meat pigment evolution was assessed by the spectrophotometric indexes. R (∞)(632)- R (∞)(614); K S (614)- K S (632) and the K S (630)- K S (580) indexes were found to be the most significant to represent the difference between the two groups.