A Review of Polarized Light Microscopy in Food Science

Some of the basic principles of polarized light microscopy are explained, followed by the problems involved in making automated measurements for meat samples with automated pH changes. Polarized light microscopy is then applied to meat samples on a tilting microscope stage to separate diffuse subsurface reflectance from the gloss of surface reflectance, to explain what is happening when a slice of meat is examined at the macro level in a conventional colourimeter. When meat is cooked, tough connective tissues may be gelatinized, thus increasing meat tenderness. This may be detected by a loss of birefringence using a polarizing microscope. The optical basis of starch granules in polarized light is explained as an interaction of the radial crystalline structure of starch interacting with the rectilinear orientation of a microscope polarizer and analyser.