postmortem muscle

Postmortem muscle refers to the changes that occur in muscle tissue after an animal's death, leading to its conversion into meat. This process involves several physiological and chemical alterations.

Key changes include:
* Rigor Mortis: Within hours of death, muscles stiffen due to the depletion of adenosine triphosphate (ATP), a molecule essential for muscle relaxation. This causes the actin and myosin filaments in muscle tissue to remain attached, holding muscles in a contracted state. Rigor mortis typically begins in smaller muscles and progresses to larger ones, with peak rigidity occurring around 12 hours after death.123
* pH Changes: Following death and bleeding, muscle cells lack oxygen and rely on anaerobic glycolysis. This process converts glycogen stores into lactic acid, causing the muscle's pH to decrease from about 7.2 in living muscle to around 5.5 in meat.4
* Protein Breakdown: Eventually, enzymatic breakdown of structural proteins, like collagen, causes muscle tissues to lose their stiffness. This process, known as resolution of rigor, contributes to the tenderness of meat over time.3