Abstract
The objective of this study was to investigate the effects of hot- and cold-boning on sarcomere length, drip loss and protein solubility of post-rigor porcine longissimus muscle. A total of ten pigs(borrow, 100$\pm$5 kg) were randomly selected at a commercial plant and the carcasses were split in half after slaughter. The longissimus muscle of the left side was dissected and chilled at 0$^{\circ}C$ after trimming of subcutaneous fat whereas the right side carcasses were served for cold-boning after chilling for 24 hrs. The temperature, pH and sarcomere length of porcine longissimus muscle were measured at postmortem 1, 3, 6, 12 and 24 hours. Drip loss, cooking loss, Minolta L*a*b*, shear force and protein solubility were measured at postmortem 24 hrs. The pH of cold-boning samples was rapidly decreased whereas temperature and sarcomere length of hot-boning samples were rapidly decreased during 24 hrs of chilling. Hot-boning muscles showed significantly (P<0.05) higher pHu and shorter sarcomere compared with cold boning muscles because of cold shortening. However, there were no significant differences in drip loss, cooking loss and shear force value between hot- and cold boned samples. The samples of hot-boning showed lower Minolta L* value and higher sarcoplasmic protein solubility compared with cold boned samples. These results suggest that the pale color changing of porcine longissimus muscle could be inhibited by hot-boning due to rapid chilling of the muscle although sarcomere length could be shortened because of cold shortening. Also these results show that hot-boning of porcine carcass could have a high protein solubility without negative effects of drip loss or tenderness of porcine longissimus muscle.
