Changes in nitrosohemachrome lead to the discoloration of spiced beef during storage

• The pigment in spiced beef is pentacoordinate mononitrosylheme. • pH value of spiced beef is unfavourable for its color stability. • Oxidation is responsible for the discoloration of spiced beef. • Water loss promotes the process of oxidation. The discoloration of spiced beef during storage is a severe problem that limits the shelf life of products. This study explored the associations between discoloration and pH, water, lipid oxidation, and protein oxidation. Electron paramagnetic resonance and UV–Vis spectroscopy illustrated that the pigment of spiced beef was a pentacoordinate mononitrosylheme compound and its conjugated structure changed during storage. The low-field NMR and magnetic resonance imaging results showed that the mobility of water increased, and the water content decreased with the extension of storage time. Multivariate analysis showed that color attributes were negatively correlated with oxidation. The oxidation of nitrosohemachrome was the primary reason for the lightness ( L *) and redness ( a *) decline in spiced beef. In addition, water loss exerted a promotion function in the oxidation process. This study provides valuable information on maintaining the quality of spiced beef during storage.