Label-Free Optical Investigation of Structural and Thermal Changes in Fat and Lean Beef under Frozen Storage

Area of Science:

• Food Science
• Biophysics
• Materials Science

Background:

• Understanding the impact of frozen storage on meat quality is crucial for the food industry.
• Assessing microstructural and thermal stability of beef during household frozen storage requires advanced analytical techniques.

Purpose of the Study:

• To evaluate the microstructural and thermal stability of beef fat and lean meat during 56 days of household frozen storage (-18°C).
• To explore the utility of Brillouin spectroscopy, Raman spectroscopy, Differential Scanning Calorimetry (DSC), and Fluorescence Lifetime Imaging Microscopy (FLIM) for non-destructive meat quality assessment.

Main Methods:

• Utilized Brillouin spectroscopy to measure mechanical stiffness (Brillouin shift and FWHM).
• Employed Differential Scanning Calorimetry (DSC) for thermal property analysis (ΔH, Tm).
• Applied Raman spectroscopy and Fluorescence Lifetime Imaging Microscopy (FLIM) for chemical and microstructural characterization.

Main Results:

• Mechanical stiffness and thermal metrics of beef fat and lean meat remained stable within experimental uncertainty throughout 56 days of frozen storage.
• Autofluorescence lifetime constants and Brillouin shifts effectively discriminated between fat and lean meat domains in a label-free manner.
• Raman spectroscopy showed minimal chemical contrast between the tissue types.

Conclusions:

• Household frozen storage at -18°C effectively preserves the microstructure and thermal behavior of beef fat and lean meat over two months.
• The combination of optical (Brillouin, FLIM) and calorimetric (DSC) methods provides a sensitive, non-destructive framework for assessing beef quality.
• These techniques offer potential for real-time quality control in the meat industry.