Question

Postmortem tenderisation of meat occurs primarily due to:

• A. Lipid oxidation
• B. Proteolysis of muscle proteins
• C. Glycolysis
• D. Myoglobin denaturation

Hint:

Tender meat = protein breakdown. Always associate tenderness with proteolytic enzyme activity (calpains, cathepsins).

Answer 1

The Correct Option is B

Concept: Postmortem tenderisation is the process by which meat becomes softer after the animal has been slaughtered. This occurs due to biochemical changes in muscle tissue, mainly involving the breakdown of structural proteins by enzymes. The most important process responsible for this is proteolysis, which is the enzymatic degradation of proteins.

Step 1: Understanding postmortem changes in meat.
After slaughter, oxygen supply stops, and muscle metabolism shifts:
• Glycolysis continues anaerobically
• Lactic acid accumulates
• pH decreases Initially, meat becomes stiff due to rigor mortis.

Step 2: What happens after rigor mortis?
After rigor mortis, the muscle gradually becomes tender. This is known as postmortem tenderisation. The key mechanism behind this is:
• Breakdown of muscle proteins such as actin, myosin, and connective tissue proteins
• Action of proteolytic enzymes like calpains and cathepsins

Step 3: Evaluating each option.
• Option (A): Lipid oxidation
This leads to rancidity and off-flavors, not tenderness. Hence incorrect.
• Option (B): Proteolysis of muscle proteins
This directly causes weakening of muscle structure, making meat softer and more tender. Hence correct.
• Option (C): Glycolysis
Glycolysis produces lactic acid and lowers pH, which is important but not the main cause of tenderisation. Hence incorrect.
• Option (D): Myoglobin denaturation
This affects color changes in meat, not tenderness. Hence incorrect. Final Conclusion:
The primary cause of postmortem tenderisation is enzymatic breakdown (proteolysis) of muscle proteins. Therefore, the correct answer is option (2).