Iridescence in Meat Caused by Surface Gratings

Area of Science:

• Food Science
• Optics
• Materials Science

Background:

• Muscle tissue exhibits iridescence due to its photonic structure, specifically well-ordered gratings formed by protruding fibrils.
• This optical phenomenon can be misinterpreted by consumers as an indicator of product quality.
• Understanding and quantifying this iridescence is crucial for accurate product assessment.

Purpose of the Study:

• To explain the fundamentals of iridescence in muscle tissue.
• To develop a method for quantitatively measuring iridescence caused by diffraction gratings on pork muscle surfaces.
• To investigate methods for minimizing or removing this optical effect.

Main Methods:

• Theoretical discussion of iridescence as a light phenomenon.
• Quantitative measurement of iridescence using reflection spectrophotometry.
• Real-time monitoring of spectral measurements during controlled drying of muscle tissue gratings.

Main Results:

• The intensity of diffraction significantly diminishes upon drying the surface gratings.
• Controlled drying at 50 °C for 2 min reduced diffraction intensity.
• The diffracted light wavelength was measured at 585 ± 9 nm, suggesting a blazed surface grating.

Conclusions:

• The study provides a quantitative method to measure iridescence in pork muscle tissue.
• Findings suggest that diffraction is caused by a blazed surface grating.
• Guidelines can be developed to alter surface microstructure and minimize iridescence, thereby removing the misleading optical effect.