Effects of meat quality and storage on the breakdown of adenosine triphosphate in muscle from swine.

The quality of pork is dependent on animal genotype, pre-slaughter handling, processing, maturation, and storage. We investigated the pattern of adenosine triphosphate (ATP) breakdown as it related to these factors. Samples of the thoracis portion of the longissimus dorsi muscle were obtained from 19 randomly selected German Landrace-Pietrain crossbreed swine. Based on their 40 min post-mortem pH and electrical conductances, three groups were classified: (1) PSE meat, pH ≤ 5·6 and conductance >10 mS (n = 7); (2) intermediate quality, pH 5·6-6·0 and conductance between 4 and 10 mS (n = 5); and (3) normal quality, pH ≥ 6·0 and conductance < mS (n = 7). Hence, the animals investigated included those susceptible to malignant hyperthermia (porcine stress-syndrome). Twenty-four hours post mortem samples were evaluated for the following parameters: ATP metabolism, pH values, electrical conductance, meat colour, water binding capacity, shear force and general composition (i.e. total protein, fat, mineral and water contents). Muscle composition was the same in each group, but for the other parameters there were clear differences. Following different storage periods and conditions (1 or 5 days at 4°C and 27 days at -18°C), the degree of ATP metabolism as well as general meat quality (i.e. including sensory evaluation) were reassessed. Samples from the pre-selected groups became less discernible following prolonged storage. In all animals, the pattern of ATP breakdown was similar, the major metabolites including inosine monophosphate, hypoxanthine, adenosine monophosphate, and inosine. The degree of breakdown was dependent on the duration and temperature of storage, but not on animal type. The muscular samples for the intermediate and normal muscle groups, which were stored for 27 days at -18°C, were given the highest sensory evaluation scores. The simple HPLC measurement of ATP metabolism was considered as a useful means to assess appropriate storage.