The buffering capacity of porcine muscles.

The aim of this study was to investigate the buffering capacity (BC) of five porcine muscles. The pH of muscles with zero lactate was also estimated. The BC was calculated on the basis of the amount of lactate accumulating in the muscle between two sampling times and the simultaneous pH decline. Two muscle samples were obtained from each muscle (n=13-36): one as soon as possible after slaughter and the other 24 h post-mortem. The BCs (mmol lactate/(pHkg)) were in the light gluteus superficialis, longissimus dorsi and semimembranosus muscles 48.3±8.8, 48.6±9.2 and 46.8±13.0, and in the dark infraspinatus and masseter muscles 45.3±13.1 and 32.0±11.5, respectively. The dark masseter muscle differed significantly from the other muscles studied (p<0.01). The estimated pH values of muscles with zero lactate were in the gluteus, longissimus dorsi, semimembranosus muscles 7.14±0.06; 7.18±0.06; 7.38±0.08, and in the infraspinatus and masseter muscles 6.87±0.07; 7.03±0.08, respectively. It was suggested since lactate is continuously formed in the muscles, the resting pH of living light and dark muscles may, however, be the same. The approach used in this study to determine the BC resulted in values which are close to values previously reported in the literature (measured by using titration curves).