This work studied 12 horses at different ages butchered in a slaughterhouse in Minas Gerais State, Brazil (SIF 1803) and evaluated temperature, pH, sarcomere length in different periods after slaughter (1h, 5h, 8h, 10h, 12h, 15h, and 24 hours) as well as the shear force (meat tenderness) of the Longissimus dorsi and Semitendinosus muscles, aiming at characterizing the rigor mortis onset in the meat during industrial processing. The chilly room temperature varied from 10.2°C to 4.0°C, and the mean initial carcass temperature was 35.32°C and the final one was 4.15°C. The mean initial pH of Longissimus dorsi was 6.49 and the final one was 5.63; the mean initial pH of Semitendinosus was 6.44 and the final one was 5.70. The smallest sarcomere size obtained in both muscles occurred at 15 hours postmortem, and the sarcomere lengths were 1.44 µm and 1.41 µm, respectively. The meat from adult horses was tougher than that from young ones (p<0.05), and the Semitendinosus muscle was tougher than Longissimus dorsi muscle.
horse carcass; muscle; rigor mortis; tenderness
