Understanding Post-Slaughter Physicochemical Changes in Meat

Introduction

When an animal undergoes slaughter, its muscles experience a remarkable transformation. They shift from living tissue to the delicious meat we enjoy. This process involves a series of complex physicochemical changes that ultimately determine the quality of the meat. Understanding these changes and the factors that influence them is crucial for meat producers, processors, and consumers alike. In this article, we will dive deep into the world of post-slaughter physicochemical changes in meat and explore how various factors, from animal handling to environmental conditions, impact the final product.

Physicochemical Changes Post-Slaughter

pH Changes

One of the most significant changes that occur in meat after slaughter involves a drop in pH. As the animal’s muscles transition from aerobic to anaerobic metabolism, lactic acid accumulates due to glycogen breakdown. This process causes the pH to decline from a neutral level of around 6.5 to approximately 5.6–5.2 within the first 24 hours post-mortem. The rate and extent of this pH drop serve as crucial indicators of meat quality, influencing tenderness, color, and water-holding capacity (WHC).

Color and Water Holding Capacity

The color of meat closely ties to pH changes. As the pH decreases, meat can take on a paler appearance. Conversely, higher pH levels—often resulting from poor handling or stress—can lead to the development of dark, firm, and dry (DFD) meat. Additionally, pH affects the WHC of meat. Lower values lead to increased cooking losses and reduced juiciness.

Texture and Tenderness

After slaughter, the structural integrity of muscle fibers changes, resulting in altered meat texture. The onset of rigor mortis, where muscle fibers stiffen, occurs within hours of death and can last for several days. The resolution of rigor mortis and subsequent aging processes enhance tenderness. However, these changes depend on factors such as the duration of aging and storage temperature conditions.

Factors Influencing Post-Slaughter Changes

Handling and Transportation

Proper handling of animals before and during slaughter significantly impacts meat quality. Stressful conditions, such as overcrowding, high temperatures, and long transportation times, can lead to rapid pH declines and associated quality defects, including pale, soft, and exudative (PSE) meat. Meat producers must implement proper handling techniques, such as minimizing stress and ensuring adequate rest periods before slaughter, to maintain meat quality.

Environmental Conditions

Heat stress notably exacerbates the decline in meat quality. Animals exposed to high temperatures before slaughter exhibit increased glycolytic activity, leading to faster pH drops. This can result in undesirable meat characteristics, such as reduced brightness and increased ultimate pH values.

Genetic and Physiological Factors

The breed, age, and overall health of the animal also play a role in post-slaughter meat quality. Different species and breeds respond differently to stress and handling, which can influence the final physicochemical properties of the meat.

Mitigation Strategies

To minimize the negative impact of post-slaughter changes on meat quality, producers can employ several strategies:

1. Proper Animal Handling: Reduce stress by minimizing handling, transportation time, and exposure to high temperatures.
2. Electrical Stimulation: Applying electrical stimulation to carcasses can accelerate the onset of rigor mortis and improve tenderness.
3. Carcass Suspension: Suspending carcasses by the Achilles tendon can enhance tenderness by stretching the muscle fibers.
4. Chilling and Aging: Rapidly chilling carcasses followed by controlled aging can improve tenderness and flavor.
5. Genetic Selection: Selecting breeds and animals with desirable meat quality traits helps produce consistently high-quality meat.

Conclusion

Post-slaughter physicochemical changes in meat are complex and multifaceted. Various factors, ranging from animal handling to environmental conditions, influence these changes. By understanding these processes and the factors that drive them, meat producers, processors, and consumers can work together to ensure the consistent production of high-quality meat. Through the implementation of best practices, technological advancements, and ongoing research, the meat industry can continue to evolve and meet the ever-changing demands of consumers worldwide. 

For more pearls of Vets Wisdom:

https://wiseias.com/partitioning-of-food-energy-within-animals/