Imaging optical diffuse reflectance in beef muscles for tenderness prediction

The objective of this study was to investigate the potential of a novel optical reflectance imaging method to predict beef tenderness. Two-dimensional (2D) optical reflectance in beef muscles induced by a point incident light was acquired. A set of five parameters were extracted from each reflectance image to describe quantitatively the reflectance profiles. Two parameters, q and B, were derived by numerically fitting the equi-intensity contours of the reflectance pattern. Two spatial gradients were calculated along the directions parallel and perpendicular to muscle fibers and total scattering intensity was obtained by excluding the specular reflectance. This method was applied to analyze 2D images of optical diffuse reflectance in 336 beef samples obtained from 14 steers in which large variations in tenderness were generated by altering animal genetics, suspension method and aging time as well as utilizing muscles varying in their inherent tenderness. Tenderness was evaluated using Warner–Bratzler shear force (WBSF). The effects of animal breed, muscle, types of suspension, and aging were investigated and results indicate that the scattering intensity measured at 1-d was correlated (R2 = 0.50 at λ = 720 nm) with 10-d WBSF in M. longissimus dorsi muscles; and the q parameters measured at 1-d was correlated (R2 = 0.46 at λ = 720 nm) with 10-d WBSF in M. psoas major muscles. These results show analyzing 2D reflectance images of meat surfaces provides valuable information regarding the physical characteristics of meat that are responsible for beef tenderness.