Effect of vitamin E supplementation and diet on fatty acid composition and on meat colour and lipid oxidation of lamb leg steaks displayed in modified atmosphere packs

Groups of 8 lambs were allocated to one of five concentrate diets supplemented with all-rac-α-tocopheryl acetate containing 30 (C30), 60 (C60), 120 (C120), 250 (C250) and 500 (C500) mg/kg dry matter. Two other groups were fed grass silage and 400 g/day concentrate with 60 (S60) or 500 (S500) mg α-tocopheryl acetate/kg dry matter. Within diet, vitamin E level did not affect growth performance or carcass characteristics. Basal diet did not affect final live weight, conformation and fatness scores. M. semimembranosus from S lambs contained more α-tocopherol than that of C lambs on the same intake and by day 6 in MAP (75%O2/25%CO2) chroma and a* were below acceptable levels in C30 lambs. TBARS were higher in C30 and C60 muscle than in other treatments (P < 0.001) after 3 and 6 days display. Muscle fatty acid composition varied with basal diet but lipid oxidation depended more on vitamin E concentration with an initial concentration of 1.9 μg/g muscle preventing significant lipid oxidation.

► Groups of lambs were fed concentrate and one of five concentrations of vitamin E.
► Two groups were fed grass silage and one of two concentrations of vitamin E.
► Silage-fed lambs had more SM muscle vitamin E than equivalent concentrate-fed animals.
► Lower levels of vitamin E gave significant colour deterioration within 6 days in MAP.
► An initial 1.9 μg vitamin E/g lamb SM muscle prevented significant lipid oxidation.