Changes in concentration of sarcoplasmic free calcium during post-mortem ageing of meat

We studied post-mortem changes in the concentrations of sarcoplasmic free calcium in various meats to clarify the tenderisation mechanism of meat, taking sufficient care to prevent contamination with calcium ions other than those in meat. When minced meats were homogenised and concentrations of soluble calcium ions were determined by atomic absorption spectrophotometry, it was found that the concentration of free calcium increased, the rate of increase varying depending on the species, and reached a narrow range of 210–230 μM regardless of the anatomical class of skeletal muscle, chronological ageing or animal and fowl species. The calcium concentration was 100 nM immediately post-mortem when homogenisation was performed in the presence of 2 mM ATP. Phospholipids were liberated from the sarcoplasmic reticulum during ageing of meat. It is likely that calcium ions leak into the sarcoplasm through channels formed by phospholipid liberation.