Refractometry of pork muscle and beef connective and adipose tissue

Bulk refractive index (RI) was measured with ail Abbe refractometer using a red laser for transmittance (T) and a green laser for reflectance, The critical angle, although obscured by scattering, was detected subjectively at the red-green boundary. The refractometer also was operated under computer control. detecting R1 photometrically. Pork longissimus thoracis (n = 20) had higher R1 than biceps femoris (1.357+/-0.004 versus 1.352+/-0.005. respectively. P<0.001), Longissimus thoracis also had lower Japanese pork colour scores (JPCS) than biceps femoris (2.92+/-0.37 versus 3.87+/-0.48, respectively, P<0.001). In pooled samples (n=40), RI was correlated with JPCS, r= -0.55, P<0.001. RI of bovine tendon (n=10) was higher than for adipose tissue (1.415+/-0.009 versus 1.343+/-0.001, P<0.001). Refraction may contribute to the inverse relationship between meat pH and paleness, and may affect signals from fibre-optic meat probes. (C) 2002 Elsevier Science Ltd. All rights reserved.