ABSTRACT
Carcasses from 36 Large White gilts, 70-80 kg live weight, were randomly allocated to three experimental groups. Pigs in the first group were electrically stimulated with low voltage during bleeding (85v, 14Hz for 64 s) and split before cooling. The left sides were rapidly chilled in air at -15°C for 75 min and then at 1°C until 24 h post-slaughter; right sides were chilled conventionally in air at 1°C for 24 h. In the second group, two different treatments were used 20 min post-slaughter: left sides were stimulated with low voltage, and right sides with high voltage (700 v, 12·5 Hz for 90 s). Both sets of sides were chilled rapidly. Carcasses from the third group were not stimulated, and sides chilled either rapidly or conventionally. Drip loss, colour and texture were measured in M. longissimus thoracis et lumborum at 3 and 10 days post-slaughter. At 3 days post-slaughter the high voltage, treatment gave meat which was the most tender, was not pale and lost no more drip than unstimulated controls. Low voltage stimulation during bleeding gave meat which was 18% more tender than the unstimulated controls, but the improvement in tenderness was not as great as the 28% achieved with high voltage. Unexpectedly, low voltage stimulation applied 20 min after slaughter, was almost as effective in improving tenderness (by 17%) as low voltage applied during bleeding. Tenderness improved from 3 days to 10 days in all stimulated samples, but not in unstimulated controls. The results suggest a degree of coldtoughening in the latter, even with conventional chilling, and a positive effect of electrical stimulation on tenderness, independent of its protective action against cold-shortening.
ABSTRACT
Two groups of 40 castrated male pigs were selected at random in an abattoir from pigs arriving from two farms, situated 650 km (group A) and 180 km (group B) from the plant, respectively. The animals were kept in lairage overnight and slaughtered the following morning. At slaughter, samples of blood were collected to determine serum levels of some enzymes [lactic dehydrogenase (LDH), glutamic oxaloacetic transaminase (GOT) and glutamic phosphatase transaminase (GPT)]. Measurements of pH were then taken on the Longissimus thoracis at the level of the last rib 45 min, 3 h and 24 h post mortem. After overnight chilling of the sides at +2°C, a portion of the Longissimus thoracis was removed for colour and drip measurements. Results show that distance travelled affects pH values at 45 min and 24 h, group A presenting higher values than group B (P < 0·001). Drip loss did not differ significantly between the two groups, while group A showed lower values of L (∗) and higher a (∗) values than group B (P < 0·05 and P < 0·01, respectively), with no differences in the mean values of b (∗). In group A, a higher value of LDH was observed (P < 0·001) than in group B. GOT and GPT showed no significant difference between the two groups. It is concluded that, although some significant effects of treatment were recorded on some quality traits, the magnitude of the differences are not considered of much practical significance.