Transverse anisotropy in beef muscle

In beef sternomandibularis muscles, a variety of treatments—tetanic contraction, cold shortening, cooking shortening and swelling in alkali—caused dimensional changes which differed markedly with the direction chosen within a plane perpendicular to the fibre direction. In all cases a marked increase (up to twice) occurred in the narrow dimension of the muscle, with little change in the wide dimension. In the cooked meat, shear force across the fibre was independent of the transverse direction chosen whether the muscle was relaxed or cold shortened. The effects were also seen in rectus abdominis and psoas, but not in longissimus dorsi muscles. It is suggested that anisotropy is a result of differing organisation of connective tissue in the two directions, although there was little histological evidence. The force to shear parallel to the fibres varied with direction in a manner consistent with this view.