Histological Contribution of Collagen Architecture to Beef Toughness

The relationship between shear force value and collagen architecture of connective tissue of the longissimus thoracis (LT) muscle of Japanese Black (n = 10) and Brown (Kumamoto) (n = 5) steers (body weight: 688.4 +/- 8.6 kg as average and standard error) was investigated. There were negative correlations between the shear-force value and lipid content (n = 15, R(2) = 0.3709, P < 0.01) and protein content and lipid content (n = 15, R(2) = 0.6748, P < 0.01). Shear force value and collagen content (n = 15, R(2) = 0.4344, P < 0.01) were positively correlated. In scanning electron microscopic photographs of the macreated preparation, the perimysium of the high-lipid LT muscle was broken down compared with the low lipid LT muscle. The endomysium in all LT muscle fibers showed similar architecture. The fine surface cover of reticular collagen fibers around an adipocyte was observed in the high-lipid LT muscle perimysium. These results suggested that the shear-force value of the LT muscle was related to change in collagen architecture and of the perimysium in particular.