Sarcomere length determination using front-face fluorescence polarization

Area of Science:

• Muscle physiology
• Biophysics
• Food science

Background:

• Tryptophan is a key intrinsic fluorophore in muscle proteins.
• Proteins exhibit preferential alignments relative to muscle fiber direction.
• Muscle structure impacts meat quality characteristics like toughness.

Purpose of the Study:

• To estimate post-rigor sarcomere length in beef using tryptophan fluorescence.
• To develop an in-line detection method for cold shortening in meat.
• To correlate fluorescence anisotropy with meat structure and quality.

Main Methods:

• Utilized a theoretical model and front-face fluorescence polarization.
• Measured tryptophan fluorescence anisotropy.
• Assessed sarcomere length in beef samples (1.6–3.4 μm).

Main Results:

• Fluorescence anisotropy varied between normal, stretched, and cold-shortened beef samples.
• Cold shortening led to fiber misalignment, reducing anisotropy.
• The method successfully estimated sarcomere length.

Conclusions:

• Fluorescence anisotropy is a viable indicator of sarcomere length and cold shortening in beef.
• This technique can be applied for in-line quality control in the meat industry.
• Detecting cold shortening early can mitigate meat toughness.