Photometry of light passing longitudinally along red and white pork muscle fibers at pH 5.5 and 7.0

Abstract

Light passing approximately 1 mm along the longitudinal axes of red and white muscle fibers was measured in thick transverse sections of pork psoas minor and gluteus medius. No birefringence was detected. From 460 to 700 nm, red fibers always had lower ( P <0.01) transmittance ( T) than white fibers. Differences persisted after 2 h perfusion with 0.2 M phosphate buffer and were unlikely to have been caused by myoglobin in red fibers. Elevating pH from 5.5 to 7.0 increased T in both red and white fibers ( P <0.001 at 400 nm and from 430 to 700 nm, n=20). This supports myofibrillar refraction contributing to pork paleness. Attenuation in red fibers may weaken pork paleness predicting fluid losses.