Changes in intramuscular connective tissue and collagen solubility of bovine m.semitendinosus during retorting

Vacuum-packed slices of bovine m.semitendinosus (ST) muscle were retorted to internal temperatures of 50, 60, 70, 80, 90, 100 and 121°C. Changes in the microstructure of the endomysium and perimysium were evaluated using a scanning electron microscope (SEM). Changes in solubility of intramuscular collagen were also estimated. In samples heated to 50°C changes in intramuscular connective tissue were not seen. At 60°C granulation of the perimysium and sarcolemma was seen, and on longitudinal sections, as well as granulation, fibrous structures of perimysium were observed. At 70°C increased granulation was observed. In the range 80-121°C progressive compression of the meat structure was seen in the transverse sections. The percentage of soluble collagen in the meat changed little up to an internal temperature of 60°C, but at 70°C it almost doubled, and in the range 80-121°C drastically decreased.