Optical characteristics of deep pectoral myopathy in turkey carcasses

When eviscerated turkey carcasses are illuminated with white light from a 100 W lamp in the body cavity dorsal to the sternum, about 90% of carcasses with deep pectoral myopathy can be detected subjectively. With this method, subjective detection is more reliable than photometric detection. When a fiber-optic probe is placed in direct contact with a lesion, the absorbance spectrum of reflected light is radically different to the spectrum from normal muscle, and three types of lesions can be identified (red-purple, green, and yellow). However, the presence of lesions is masked by even a shallow depth (approximately 1 cm) of normal muscle between the lesion and the probe. A combination of both optical methods might enable carcasses to be inspected without slashing the breast muscles of all the carcasses from flocks of suspect birds, but the whole length of the supracoracoideus on each side would have to be traversed by the fiber-optic probe. For a fiber-optic detection system in the abattoir, the simplest diagnostic characteristic would be the ratio of two wavelengths (480/550 nm). The average ratio for normal muscle was .68. The average ratios for lesions were from 1.17 to 1.38.