Cheese Microstructure Image Analysis

Many varieties of cheese are salted by immersion in brine (salty water) instead of by direct salting of the curd during cheese making. Brine salting causes large gradients of salt and moisture to develop within the structure of blocks of cheese. In general, moisture will be low and salt content will be high at the surface of a brine-salted cheese. The salt uptake behavior is affected by brine concentrations. There appears to be some critical concentration of salt in brine above which there is a large negative impact on salt uptake due to the creation of a barrier layer at the surface of the block of cheese.
Salt uptake is related to cheese porosity, tortuosity of the channels of aqueous phase within the structure of cheese, viscosity of the acqueous phase, and interaction of sodium with the protein matrix. The objective of this research was to determine how brine concentration at constant temperature influences the microstructure of the surface barrier layer that develops in Ragusano cheese during brine salting.
Among the factors contributing to salt uptake, porosity and tortuosity can be evaluated by applying image processing and computer graphics techniques to 2D and 3D cheese scans. Cheese samples are scanned using either Scanning Electron Microscopy (SEM), or Computed Tomography (CT). The scans are processed to evaluate porosity and tortuosity. The following figure shows an example of pore estimation on a SEM image (the dynamics of the scans is reduced to fit the display range).

(a) Input SEM scan	(b) Pore detection	(c) Porosity