Abstract
The objective of this study was to recognize the specificity of microstructural changes of DFD sheep m. Longissimus dorsi during its ripening, and to try to explain them by biochemical and physicochemical amendments of meat. The fresh (4 h post mortem) DFD sheep m. Longissimus dorsi with pH1 = 6.95 stored at 2 ± 2°C was used. The microstructure, degree of proteolysis, color properties, water holding capacity and pH of DFD sheep meat were evaluated during 5d of storage. The shortenings of the sarcomeres and typical alternation of light and dark bands were established after 48h storage of DFD sheep muscles. Simultaneously, pH and water holding capacity decreased with 16.5% and 50.6% resp. (p ≤ 0.05), accompanied with the lowest protein solubility, and a disappearance of myosin heavy chains. On the 3d post mortem sarcomeres were partly regenerated and their native structure was recovered, A- and I-disks were visible, and Z-lines were undamaged. On the 4d post mortem was found large gap formation in sarcomeres and difficulty recognizable A- and I-disks. On the 5d post mortem the pH and water holding capacity were similar (p > 0.05) with the initial values but free amino nitrogen decreased with 34.5%.