Effect of interface conditions on the optoelectronic measurement of carcass meat quality

Fiber optic light guides were used to illuminate the interiors of isolated meat samples or parts of commercial carcasses and to sample the light within. To maximize the dynamic range, an array was used to set the gain and high voltage of the photomultiplier at each wavelength. Optical fibres in contact with lean meat returned far less light than fibers just above the meat surface since the high specular reflectance from the rough surface of wet meat was by-passed. The formation of oxymyoglobin on aerobocally exposed meat surfaces was detected. Metabolic changes in the meat after slaughter caused progressive changes around 400 nm in ratiometric spectra. Reflectance from lean meat was increased when optical fibers were perpendicular to muscle fibers and was decreased when optical fibers were parallel and coaxial with muscle fibers. Layers of adipose tissue within the meat increased reflectance but this was temperature-dependent. Adipose tissue reflected more light at colder temperatures. Connective tissues (collagen and elastin) within meat fluoresced with a peak excitation around 370 nm and peak emissions around 440 nm and (or) 510 nm (depending on the biochemical type). The effect of fluorescence was minimal in ratiometric measurements made on meat with only a single monochromator.