English abstract
Two experiments were conducted to study the effect of low voltage electrical stimulation on histochemical, structural and meat quality characteristics of Omani camel carcasses. The first experiment was carried out to evaluate the effects of stimulation and ageing (2 vs. 7 days) on meat quality of four age groups of camel (1-3, 4-6, 7-9 and 10-12 years old). Warner-Bratzler shear force, pH, sarcomere length, myofibrillar fragmentation index, expressed juice, cooking loss and L*, a*, b* colour were measured in 72 camels. Age of camel and electrical stimulation had a significant effect on meat quality of Longissimus thoracis muscle. The histochemical staining properties of the myosin ATPase and succinate dehydrogenase stains were also evaluated. Electrical stimulation resulted in a significantly (P<0.05) more rapid muscle pH fall of muscle during the first 12 hr after slaughter. Muscles from electrically-stimulated carcasses had significantly (P<0.05) lower pH values, longer sarcomeres, lower shear force value and higher expressed juice than those from nonstimulated ones. Electrically-stimulated meat was significantly (P<0.05) lighter in colour than non-stimulated based on L* value. Muscles of 1-3 year camels had a significantly (P<0.05) lower shear force value, and pH, but longer sarcomere, and higher myofibrillar fragmentation index, expressed juice, and lightness color (L *) than those of the 10-12 years camels. The proportions of Type I, Type IIA and Type IIB in camel muscle were 25.0, 41.1 and 33.6%, respectively. Muscle samples from 1-3 year camels had significantly (P<0.05) higher Type 1 and lower Type IIB fibres compared to those from 10-12 year camel samples. These results indicated that age and electrical stimulation had a significant effect on camel meat quality.
The second experiment aimed to evaluate the effect of splitting carcasses and stimulation on histochemical, structure and meat quality characteristics of two age groups camels (1-2 vs. 8-10 year old). Thirty camels were randomly assigned to one of four treatments: non-stimulated and electrically-stimulated; unsplit carcasses and split carcasses. The split carcasses were longitudinally split along the vertebral column. A low voltage electrical stimulation was applied 20-30 min post-mortem. The Longissimus thoracis muscle pH, sarcomere length, myofibrillar fragmentation index, shear force, expressed juice, cooking loss and CIE L*, a*, b* colour values were measured. The histochemical staining properties of the myosin ATPase and succinate dehydrogenase stains were evaluated. Electrical stimulation resulted in a significantly (P<0.05) more rapid pH fall in muscle during the first 12 hrs postmortem. Muscles from stimulated samples had significantly (P<0.05) lower pH, longer sarcomere, lower shear values than those from non-stimulated ones. Myofibrillar fragmentation index and expressed juice were significantly (P<0.05) higher for stimulated than for non-stimulated samples. Meat from stimulated samples was significantly (P<0.05) lighter (L *) in colour than non-stimulated samples. There were no differences in muscle quality between split and unsplit carcasses. Muscles of 8-10 year old camels had significantly lower expressed juice, cooking loss, darker (L *) more red (a*), more yellow (b*) and higher pH and myofibrillar fragmentation index than those from 1-2 year old animals. This experiment indicated that electrical stimulation improves quality characteristics of meat from unsplit and split carcasses.
