Effect of beef ultimate pH and large structural protein changes with aging on meat tenderness

• Beef pHu plays a critical role in the degradation of large structural proteins.
• Degradation of titin, nebulin, filamin and myosin is related to meat tenderness.
• The degradation profiles were substantially different between muscle pHu groups.
• Fast degradation of large structural proteins is a key factor in meat quality.

This study investigated the effect of ultimate pH (pHu) in beef on the degradation of large structural proteins during refrigerated storage using SDS-PAGE. M. longissimus dorsi from bull carcasses were selected and classified into three groups: low pHu (≤ 5.79), intermediate pHu (5.80–6.19) and high pHu (≥ 6.2) muscles. Samples were then stored at − 1.5 °C for 1, 2, 7, 14, 21 and 28 days. Meat tenderness was measured at each aging time. Depending on meat pHu, different protein patterns and degradation rates of structural proteins were found. Rapid changes of large structural proteins took place within 48 h post mortem. Besides titin and nebulin, degradation of filamin was clearly revealed. Two more large protein bands corresponding to myosin family members also exhibited fast decline with storage time. It suggested that the fast degradation of these proteins is a key factor in the improvement of meat tenderness.