Analyzing pH-induced changes in a myofibril model system with vibrational and fluorescence spectroscopy

Area of Science:

• Food Science
• Biophysics
• Analytical Chemistry

Background:

• Postmortem pH decline significantly impacts meat quality attributes, including water-holding capacity.
• Understanding pH-related biochemical changes in meat is crucial for predicting and controlling quality.

Purpose of the Study:

• To investigate protein and amino acid modifications in pork myofibrils across different pH levels.
• To evaluate the efficacy of Raman, FT-IR, NIR, and fluorescence spectroscopy in detecting pH-induced changes.

Main Methods:

• Pork myofibril extracts were analyzed at three distinct pH levels (5.3, 5.8, and 6.3).
• Four spectroscopic techniques (Raman, FT-IR, NIR, fluorescence) were employed.
• Spectra were analyzed to identify changes in protein secondary structure and amino acid side chains.

Main Results:

• Raman and FT-IR spectroscopy identified protonation of aspartic/glutamic acid and alterations in amide I-III bands as key pH indicators.
• Fluorescence spectroscopy indicated changes related to tryptophan's molecular environment.
• Near-infrared (NIR) spectroscopy provided limited insights into pH-dependent protein structural changes.

Conclusions:

• Raman, FT-IR, and fluorescence spectroscopy are valuable tools for assessing pH-related protein modifications in meat.
• These findings enhance the interpretation of spectroscopic data for meat quality assessment.
• Spectroscopic methods offer a pathway to non-destructively monitor meat quality parameters influenced by pH.