Abstract: Postmortem muscle is highly susceptible to oxidative conditions, thus leading to deterioration of meat quality in terms of tenderness, color, and water-holding capacity (WHC). Therefore, the regulation of the oxidation mechanism is a major concern in research on postmortem meat quality. Reactive nitrogen species (RNS) are free radicals and nitro compounds with high oxidation activity derived from the interaction between nitric oxide (NO) and compounds including reactive oxygen species (ROS). RNS not only regulates mitochondria to promote cellular metabolic function, but also mediates mitochondrial damage to induce cell apoptosis, thereby regulating the quality of postmortem meat. Relevant research results need to be summarized urgently. Therefore, this paper provides an overview of the production and metabolism of RNS in cells, elaborates on the mechanism by which RNS regulates normal physiological functions of cells through mitochondria, induces cell apoptosis through causing mitochondrial damage and mediates oxidation mechanism including lipid peroxidation and protein oxidation, and discusses the mechanism by which RNS affect the tenderness, color, and WHC of postmortem muscle. We anticipate that this review will provide a theoretical reference for improving postmortem ageing.

Key words: reactive nitrogen species; mitochondrial damage; cell apoptosis; oxidation mechanism; meat quality