Assessment of relative content of myoglobin, oxymyoglobin and metmyoglobin at the surface of beef

A method of calculating the relative content of myoglobin, metmyoglobin and oxymyoglobin at the surface of beef is described. It is based on measurements of reflex attenuance of incident light at the isobestic points 572, 525, 473 and 730 nm. The latter value corresponds to the achromatic attenuance of light at the meat surface and can be used as an objective measure of its lightness. It was shown that the colour image of the meat surface, and the relative amounts of these three myoglobin derivatives, are influenced by the opacity of the surface layer. A variability in the light diffusing properties of the meat surface may be considered to be the primary factor in creating differences of colour perception of meat derived from animals of the same species and of the same approximate age.