Etude de parametres physico-chimiques et biochimiques en cinetique au cours de la maturation de la viande de dromadaire.

Abstract

The aim of this study is to contribute to the determination of the age at slaughter effect’s on dromedary (Camelus dromedarius) meat caractestic during tenderization by the studying physico-chemical, biochemical and technological parameters. Twelve Sahraoui’s population dromedaries reared on extensive system and destined to commercialization are used. Three groups of age are investigated 1-4, 6-8 and 10-19 years. The Longissimus lumborum muscle excised within the first hour post-slaughter is used to characterize its contractile fiber type by the myosine heavy chains isoform separation on SDS PAGE. The evolution of pH and water holding capacity of myofibrillar proteins are characterized. The proteolysis of myofibrillar proteins during tenderization is estimated by SDS PAGE. And actin fragments are revealed by western blot analysis. Finally, the drip loss of the muscle during conservation at 5°C, is estimated. The carcass yield is the highest with 68% for 6-8 years dromedaries. The Longissimus lumborum muscle is characterized by the presence of MyHC IIa, with no effect of age at slaughter. However, significant effect of age on pH drop is noted. In average, it falls from 6.68 to 5.71; with highest value for 1-4 years dromedaries. The rate and the extent of pH fall are greater with increased age. One or two stability steps are observed. Water holding capacity of myofibrillar proteins increased with tenderization, with highest value observed for the youngest animals. Important post mortem proteolysis is seen after 10h post-slaughter for 6-8 years animals. The actin is degraded since 1h post mortem and the fragments revealed are of about 36, 33 and 31 kDa. Small fragments of about 14 kDa are generated earlier with increased age, contrary to the 26 kDa fragments. Drip loss of the muscle during conservation at 5°C is on average 7% during the 72h post mortem. The percentage of exudation is greater for the group of 10-19 years. Drip loss of the muscle generates financial losses for 10 kg of muscle varying between 300 to 600 DA.