Biochemical Changes in Muscle After Slaughter
Rigor Mortis and Its Phases
One of the most critical postmortem changes is rigor mortis. This process involves the stiffening of muscles due to ATP depletion. It occurs in four phases:
- Delay Phase: Muscles remain relaxed as ATP is available.
- Onset Phase: ATP depletes, and muscle stiffness begins.
- Completion Phase: Maximum stiffness is reached.
- Resolution Phase: Proteolytic enzymes break down muscle proteins, leading to tenderization.
The resolution phase is essential for meat tenderization, affecting its texture and overall quality. Learn more about rigor mortis and its impact on meat texture.
Postmortem pH Decline and Meat Quality
After slaughter, muscle glycogen converts into lactic acid, reducing pH. This decline affects meat color, texture, and water-holding capacity.
- Muscle pH Change: From 7.0 (neutral) to 5.6 (acidic)
- Color Shift: Purple (muscle) changes to bright red or pink (meat)
The pH drop impacts meat water retention and tenderness. Proper handling ensures better meat quality. Explore how pH decline affects meat properties.
Physical Properties of Meat Quality
Water-Holding Capacity and Meat Juiciness
Water-holding capacity (WHC) determines how much moisture meat retains. If WHC is low, meat loses more water, affecting juiciness and tenderness.
- Low pH reduces WHC
- Proper chilling methods improve WHC
- High WHC ensures tender and juicy meat
Read about techniques to enhance meat juiciness.
Factors Influencing Meat Quality
Genetic and Environmental Factors
Genetics and environment directly impact meat quality. Different breeds exhibit varied muscle composition, affecting texture and fat content.
- Breeds with higher marbling produce more tender meat.
- Environmental stress before slaughter can toughen meat.
Find out how genetics shape meat quality.
Pre-Slaughter Handling and Stress Management
Animals experience stress before slaughter, impacting meat quality. Stress increases cortisol and lactic acid, resulting in pale, soft, and exudative (PSE) meat.
To reduce stress:
- Minimize transport time
- Use low-stress handling techniques
- Provide proper rest before slaughter
Discover the impact of stress on meat quality.
Aging and Tenderization of Meat
Aging allows enzymatic breakdown of muscle proteins, improving tenderness. There are two primary aging methods:
- Wet Aging: Meat is vacuum-sealed to retain moisture.
- Dry Aging: Meat is hung in a controlled environment, enhancing flavor.
Both methods improve meat texture, making it more desirable. Understand the science behind meat aging.
Chilling and Storage Conditions
Proper chilling prevents bacterial growth and preserves meat quality. Meat should be cooled immediately after slaughter to 1-4°C.
- Rapid chilling prevents spoilage.
- Proper packaging enhances shelf life.
Explore effective meat storage practices.
Final Thoughts
The conversion of muscle into meat is a complex biochemical process influenced by pH decline, rigor mortis, water retention, and external factors. Proper handling, storage, and stress management ensure high-quality meat with better texture, flavor, and shelf life.
By understanding these postmortem changes, veterinarians, farmers, and meat producers can optimize meat production for better quality and consumer satisfaction. Learn more about modern meat science techniques.
