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| Relationship between Adenosine Monophosphate-Activated Protein Kinase (AMPK) Activity and Meat Quality of Three Different Muscles of Ujumqin Sheep Slaughtered at Different Ages |
| XUE Baoling, SONG Xiaobin |
| 1.College of Vocational and Technical, Inner Mongolia Agricultural University, Baotou 014109, China; 2.Ulanqab Inspection and Testing Center, Ulanqab 012000, China |
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Abstract This study aimed to investigate the pattern of changes in the activity of adenosine monophosphate-activated protein kinase (AMPK), glycolysis indicators and meat quality of different muscles from Ujumqin sheep during growth. The Longissimus dorsi, Biceps femoris and Psoas major of Ujumqin sheep slaughtered at 3, 6 and 9 months of age were measured for AMPK activity, muscle glycogen content, lactic acid content, hexokinase (HK) activity, pH, shear force and color. The results showed that AMPK activity had a significant negative correlation with pH24 value and redness value (a*) (P < 0.05). Shear force significantly decreased with increasing slaughter age (P < 0.05). The yellowness value (b*) of Psoas major was largest, while that of Longissimus dorsi was smallest. For Psoas major, the pattern of change in a* was the same as that of b*, while the opposite was observed for Longissimus dorsi and Biceps femoris. A significant positive correlation between muscle glycogen content and slaughter age existed for each of the muscles. Muscle glycogen content was highest in Psoas major and lowest in Biceps femoris. The pattern of change in lactic acid content was the same as that of muscle glycogen content. A significant positive correlation between HK activity and slaughter age existed for each of the muscles. The HK activity of Psoas major was largest, while that of Biceps femoris was smallest. AMPK activity significantly increased with increasing b* and muscle glycogen content, and with increasing lactic acid and HK activity for the slaughter ages of six and nine months (P < 0.05). High AMPK activity could stimulate the key glycolysis-related enzymes during phosphorylation, HK, phosphofructokinase (PFK) and pyruvate kinase (PK), resulting in a rapid pH decline, an increase in lactic acid content, the transformation of aerobic respiration to anaerobic respiration, an increase in shear force and consequently a decrease in tenderness and cooking yield, indicating that changes in AMPK activity affect postmortem glycolysis and meat quality.
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2023, Vol. 37 
