Spectrophotometry of polarised light transmitted through and reflected from slices of turkey breast meat in relation to pH and fluid losses

Fluid (purge) losses and pH of turkey breast meat were measured (n = 45). During the 24 h between slaughter and analysis in the laboratory, fluid loss during transport was 0.54 S.D. 0.43%. Mean pH at 24 h post-mortem was 5.97 +/- 0.12. Mean cooler drip from sliced meat in the following 72 h was 4._11 +/- 1.91%. Transport loss was correlated with cooler drip, r = 0.47, P < 0.001. Transport loss was correlated with pH, r = -0.42, P < 0.01. Cooler drip was correlated with pH, r = -0.35, P < 0.02. At 24 h post-mortem, slices of turkey pectoralis muscle 1 mm thick were illuminated with linearly polarised light. Spectra were measured from 400 to 700 nm in various orientations: using transmitted or reflected light, with polarised light parallel or perpendicular to the long axes of muscle fibers, and with a rotary analyzer parallel or perpendicular to the polariser. For illumination parallel with the long axes of muscle fibers, and the analyzer perpendicular to the polariser. reflectance was correlated with fluid loss during transport to the laboratory (R = 0.60, P < 0.01, using 490, 520 and 580 nm), with sample pH (R = 0.46, P < 0.05. using 570, 580 and 550 nm), and with cooler drip losses (R = 0.55, P < 0.01, using 450, 490 and 460 nm). Overall, reflectance was more useful than transmittance for predicting pH-related fluid losses. (C) 2001 Elsevier Science Ltd. All rights reserved.