Abstract: The experiment was carried out with Bamei × small tailed sheep fed in a drylot and slaughtered at 6, 12, 18 and 24 months of age (10 half male and half female animals with similar carcass weights at each age) to determine physicochemical parameters, muscle fiber characteristics, and the yield and sensory quality of instant-boiled mutton from hindquarters. The results showed that except pH24 (pH at 24 h postmortem) and the elasticity and yield of instantboiled mutton, there were significant differences in all investigated parameters of hindquarters from sheep carcasses at different slaughter ages (P < 0.05). Both hardness and chewiness were positively correlated with sarcomere length (r = 0.639 and 0.618, P < 0.05), and likewise springiness was positively correlated with muscle fiber density (r = 0.588, P < 0.05). Collagen content was inversely correlated with the yield of instant-boiled mutton (r = −0.458, P < 0.05). The color, tenderness, flavor and overall acceptance score of instant-boiled mutton from sheep slaughtered at 6 months of age were significantly better than those of sheep slaughtered at 24 months of age (P < 0.05). The sensory quality of instantboiled lamb was more popular among sensory panelists than that of sheep slaughtered at older ages. Therefore, meat from young lambs was more suitable for instant boiling than older ones.

Key words: instant-boiled mutton, months of age, raw mutton quality, muscle fiber characteristics