Proteolytic and physicochemical mechanisms involved in meat texture development.

Area of Science:

• Meat science and muscle biology
• Biochemistry and enzymology
• Food texture analysis

Background:

• Meat texture development is a complex process involving structural softening, particularly of myofibrils.
• Post-mortem changes include enzymatic proteolysis and increased muscle osmotic pressure.
• The specific proteinases responsible for post-mortem proteolysis and texture changes remain unclear.

Purpose of the Study:

• To analyze data from two approaches to identify proteinases involved in meat texture development.
• To investigate the roles of lysosomal (cathepsins) and calcium-dependent (calpains) proteinases.
• To examine the contribution of physicochemical mechanisms, such as osmotic pressure, to meat tenderization.

Main Methods:

• Reviewing studies that correlate structural/biochemical changes with meat texture development.
• Assessing which proteolytic systems can reproduce observed changes in myofibrils or muscle fibers.
• Relating meat texture changes to the tissue's proteolytic enzyme content and enzyme/inhibitor ratios.
• Investigating the impact of post-mortem osmotic pressure on myofibrillar changes.

Main Results:

• Meat texture changes are best explained by the synergistic action of lysosomal and calcium-dependent proteinases.
• Meat tenderization rate depends on the initial potential efficiency of proteinases (enzyme/inhibitor ratio), not just levels.
• Increased post-mortem osmotic pressure contributes to myofibrillar biochemical changes, correlating with tenderization rates.
• Myofibrillar structure may act as a limiting factor in the efficiency of both enzymatic and physicochemical mechanisms.

Conclusions:

• Both enzymatic (lysosomal and calpain systems) and physicochemical (osmotic pressure) mechanisms are crucial for meat texture development.
• The efficiency of tenderization is linked to the regulated activity and potential of proteinases, not solely their quantity.
• Further research on proteinase regulation and myofibrillar structure is essential for understanding meat tenderization.