Stratification of connective tissue toughness in beef roasts assessed by simultaneous fluorometry and penetrometry

Beef rib roasts were probed to measure connective tissue fluorescence and resistance to penetration at different depths. Data were collected at the aponeurosis on the surface of Longissimus thoracis (site 1), from muscle below the aponeurosis (site 2), and from a major perimysial septum within the muscle (site 3). Penetration force at site 1 was correlated with forces at site 2 (r = 0.51, P < 0.05) and site 3 (r = 0.63, P < 0.025). Fluorescence at site 1 was correlated with fluorescence at site 2 (r = 0.81, P < 0.0005) and at site 3 (r = 0.78, P < 0.005). Thus, the aponeurosis on the muscle surface is related to underlying connective tissues in strength and composition. Aponeurosis was more than three times as strong as muscle alone (P < 0.001). Failure to detect a useful relationship between aponeurosis fluorescence and strength was attributed to loss of linearity (optical saturation) as the aponeurosis wrapped around the probe.