Résumé:
Among the environmental factors, grass feeding has been reported to affect several meat quality characteristics, in particular colour and flavour. In this work we have reviewed some differences in meat colour and flavour between lambs fed concentrates and animals allowed to graze pasture. The possible factors influencing the differences have been also examined. We have examined a total of 20 experiments which report the effect of pasture vs concentrate finishing systems in Highland vs steppe, respectivelly, on lamb meat colour. The study was carried out in spring of 2014. Meat from mutton raised on concentrates is reported to be darker than meat from animals raised on pasture (P<0.05), particularly for the red index (14.05 vs. 8.01) and (12.54 vs 10.9) for the muscles of the ribs and legs. Changes in a* values appear to be driven by lipid oxidation and are strongly correlated with TBARS values (0,14 mg éq/kg vs. 0,12 mg éq/kg) and (0,11 mg éq/kg vs. 0,09 mg éq/kg), respectively. Several factors, not a specific one are responsible for this difference, variations in ultimate-pH and in intramuscular fat content between animals finished at pasture and those finished on concentrates, seem to play a major role. Diet also affects meat flavour, the analysis of Djelfa and Tiaret groups meat flavor compounds shows a predominance of many volatile compounds (p<0,05) such as Hexanal, 2-methyl-3-furanthiol and nonanal (8,92 μg/kg vs. 4,57 μg/kg), (8,88 μg/kg vs. 7,45 μg/kg) and (2,09 μ/kg vs. 1,02 μg/kg) associated with smells of green, boiling meat and orange fruit, respectively. These compounds, measured by olfactometry, derived from the oxidation of lipids and appear to be responsible for the characteristic flavor of lamb meat in the steppe compared to that generated by meat from animals from the Tiaret pastures. In sheep, pastoral flavour is mostly determined by the branched-chain fatty acids, 3-methylindole (skatole) and it seems to be mostly determined by products of oxidation of linolenic acid and its derivates which derives substantially from grass. Diet components and particularly grass regimes can affect meat colour and flavour in meat lamb.
The Algerian steppe ecosystem is very interesting in the production of typical lamb meat that can be considered as a label.
