The physical basis of meat texture: Observations on the fracture behaviour of cooked bovine M. Semitendinosus

The fracture behaviour of cooked strips of beef M. semitendinosus was studied by qualitative observation of the manner in which fracture occurred and by quantitative measurements of ultimate tensile strength, work of fracture and notch sensitivity. Qualitative observations showed that fracture started in the perimysial connective tissue in all test configurations used, resulting initially in the separation of intact muscle fibre bundles. The ultimate tensile strength along and across the fibres was ～-300kNm(-2) and ～-25kNm(-2), respectively. The qualitative aspects of fracture were explained on the basis of a uniaxial fibrous composite of strong muscle fibre bundles in a weak connective tissue 'matrix', with poor interfacial strength. Work of fracture through the perimysium was in the range 0·4 to 1·8kJm(-2). The difficulty in propagating fracture across the muscle fibre bundles was explained in terms of the material's complete insensitivity to notches running across the fibres. The results imply that the muscle fibre bundle is an important level of structural organisation as far as fracture is concerned and that the strength of the perimysium, or perimysium/muscle fibre bundle interface, is likely to have a major influence on the toughness of'the cooked meat.