Myosin Heavy Chain Composition, Rate of Dystrophin and Integrin Degradation and Meat Quality of Pig Longissimus thoracis and psoas major Muscles During Postmortem Aging

This study evaluated myosin heavy chain composition and the effect of aging time (45 min, 24 h, 96 h and 168 h) on meat quality parameters and dystrophin and integrin degradation pattern in longissimus thoracis and psoas major muscles of 24 Polish Landrace fatteners slaughtered at 100 kg body weight. It was found that m. longissimus thoracis had a greater percentage of MyHC-IIB (P≤0.05) and a significantly lower percentage of type I and IIA/IIX (P≤0.05) compared with the m. psoas major. Moreover, psoas major muscle had significantly higher (P≤0.05) pH₄₅, pH₂₄ and lower drip loss values for 45 min to 24 h, 45 min to 96 h and 45 min to 168 h than m. longissimus thoracis. Muscle type also had a significant effect on the rate of dystrophin and integrin degradation postmortem, which were significantly (P≤0.05) more rapidly degraded in the m. longissimus thoracis compared to the m. psoas major. It is concluded from the obtained results that the muscles with a greater percentage of MyHC-IIB show lower pH values, which translates into more rapid rate of integrin and dystrophin degradation. Ultimately, this may contribute to higher drip loss values during refrigerated storage.