Changes in proteasome activity during postmortem aging of bovine muscle

Area of Science:

• Biochemistry
• Food Science
• Animal Science

Background:

• Proteasomes are crucial cellular machines involved in protein degradation.
• Understanding postmortem proteasome activity is key to improving meat quality and tenderness.
• Bovine rectus abdominis muscle is a significant component of beef products.

Purpose of the Study:

• To investigate the changes in various proteasome activities in bovine muscle during early postmortem storage.
• To assess the stability of proteasome activities under physiological conditions and decreasing pH.
• To determine the potential role of proteasomes in postmortem meat tenderization.

Main Methods:

• Enzyme assays were conducted on crude extracts of bovine rectus abdominis muscle.
• Measurements included chymotrypsin-like, trypsin-like, peptidylglutamylpeptide hydrolyzing, and caseinolytic activities.
• Assays were performed at cellular pH and during the first seven days of postmortem storage at 4°C.

Main Results:

• Proteasome activities exhibited considerable stability during the first 7 days of postmortem storage.
• After 7 days, activities ranged from 40% to 76% of their initial at-death values.
• The different proteasome activities showed varying stability profiles at cellular pH.

Conclusions:

• Proteasome activities are remarkably stable postmortem in bovine muscle, even with significant pH decline.
• This stability suggests that proteasomes actively contribute to meat tenderization.
• Proteasomes likely work synergistically with other proteolytic systems to enhance meat quality.