Abstract
Meat is an important source of high-value protein providing sustainable nutrition for human health. The discolouration of meat results in significant waste, which threatens the sustainability of meat production in terms of availability, affordability, and utilisation. Advancing the knowledge of factors and underlying mechanisms for meat discolouration supports the sustainability transformation of meat production practices. Previous studies found that colour stability may be associated with signature changes in certain metabolites, including NADH, glutamate, methionine, and testosterone. This study aimed to confirm the effect of these metabolites and sex, sire, and muscle type on lamb meat colour. NADH and glutamate improved colour stability as evidenced by the increased metmyoglobin reductase activity, while methionine and testosterone had detrimental effects. Overall, lamb meat was discoloured with retail display for up to 10 days at 4 °C. The semitendinosus muscle had higher L*, b*, and hue angle and lower a* (p < 0.05) than other muscles, especially in ewes. Lamb meat from rams had a higher L* and hue angle and lower a* than the ewes (p < 0.05), especially in the colour-labile group, suggesting an interaction between sex and sire. The outcomes of this study will help make the production of meat more sustainable by assisting the meat industry in improving the selection of animals for meat production and processing practices to reduce meat waste due to discolouration.