Effects in ewe diet of rosemary by-product on lipid oxidation and the eating quality of cooked lamb under retail display conditions

Distilled dietary rosemary leaf (DRL) was tested to prevent lipid oxidation and sensory deterioration of cooked lamb under retail display conditions. Pregnant sheep were fed with a basal diet supplemented by 0%, 10% and 20% DRL. Cooked lamb fillets were stored for 0, 2 or 4 days at a temperature of 4 °C in a display cabinet and re-heated, simulating catering practices. The cooked lamb suffered rapid lipid oxidation and odour and flavour spoilage associated with slight rancidity and warmed-over flavour, and, to a lesser extent, with loss of colour and juiciness. DRL feeding delayed lipid oxidation measured as TBARS and volatile compounds, this being more effective in the first two days of storage. 10% and 20% of DRL provided equal antioxidant capacity. However, DRL feeding hardly prevented sensory deterioration, although incipient rancidity was delayed. Feeding DRL to ewes contributed to extend the shelf life of cooked lamb under retail display conditions.