Major buffering constituents in animal muscle.

1. Among the muscles of six fish species, three mammals, and a bird, white muscle of skipjack tuna showed the highest buffering capacity (BC) in the pH range 6.5-7.5, followed by the muscle of little-piked whale, chicken pectoralis minor, and mackerel white muscle. 2. Contribution of low-molecular weight components to the muscle BC was as high as 48-96%, while the contribution of muscle proteins was below 50%. 3. Histidine-related dipeptides and inorganic phosphate were found to be major buffering constituents in muscle. 4. The dipeptides accounted for the BC differences found between the species and muscle types.