Abstract: To investigate the effect of basal immunoglobulin (BSG) expression during postmortem maturation on meat quality, changes in quality indicators such as pH, cooking loss and myofibril fragmentation index (MFI), as well as energy substance and BSG contents of Qinchuan cattle meat were measured after different periods (0, 2, 4, 6 and 8 days) of postmortem aging at 4 ℃. The proteomic changes were also analyzed using 4D-label free quantification (4D-LFQ). The results showed that during the postmortem storage period, the expression of BSG showed an overall trend of initially increasing and then decreasing. The levels of the energy substances ATP, ADP, AMP and NADH showed a decreasing trend; pH and cooking loss initially decreased and then increased; MFI showed a continuous increasing trend. The correlation analysis showed that the expression of BSG was significantly positively correlated with cooking loss (P < 0.01), but negatively correlated with pH, ATP and NADH levels (P < 0.05). However, it had no significant correlation with ADP or AMP contents. Therefore, the change of BSG expression in the Longissimus dorsi muscle of Qinchuan cattle during postmortem maturation was closely related to the quality and energy metabolism of beef. Proteomics identified that BSG and its associated differential proteins had catalytic activity, hydrolase activity and proton-transporting ATP synthase activity, bound to ATP, ribonucleotides and carbohydrate derivatives in cells, and were involved in the regulation of molecular functions and hydrogen ion transport across membranes. These biological effects caused mitochondrial damage and were involved in changes in meat tenderness through energy metabolism.

Key words: basal immunoglobulin; Longissimus dorsi muscle of Qinchuan cattle; energy substance; tenderness; quality