Effect of muscle restraint on sheep meat tenderness with rigor mortis at 18°C

The effect on shear force of skeletal restraint and removing muscles from lamb m. longissimus thoracis et lumborum (LT) immediately after slaughter and electrical stimulation was undertaken at a rigor temperature of 18degreesC (n= 15). The temperature of 18degreesC was achieved through chilling of electrically stimulated sheep carcasses in air at 12degreesC, air flow 1-1.5 ms(-2). In other groups, the muscle was removed at 2.5 h post-mortem and either wrapped or left non-wrapped before being placed back on the carcass to follow carcass cooling regimes. Following rigor mortis, the meat was aged for 0, 16, 40 and 65 h at 15degreesC and frozen. For the non-stimulated samples, the meat was aged for 0, 12, 36 and 60 h before being frozen. The frozen meat was cooked to 75degreesC in an 85degreesC water bath and shear force values obtained from a 1 x 1 cm cross-section. Commencement of ageing was considered to take place at rigor mortis and this was taken as zero aged meat. There were no significant differences in the rate of tenderisation and initial shear force for all treatments. The 23% cook loss was similar for all wrapped and non-wrapped situations and the values decreased slightly with longer ageing durations. Wrapping was shown to mimic meat left intact on the carcass, as it prevented significant prerigor shortening. Such techniques allows muscles to be removed and placed in a controlled temperature environment to enable precise studies of ageing processes. (C) 2002 Elsevier Science Ltd. All rights reserved.