The FTIR spectroscopic investigations were conducted on a Bruker Vertex 70 FTIR spectrometer (Germany) equipped with a Platinum ATR cell and connected to a Hyperion 2000 IR microscope with a 15 X Cassegrain objective. IR spectra of the skin and the core of the specimens were recorded at a resolution of 4 cm -1 from 4000 to 600 cm -1 using the ATR cell. IR microscopic mappings were recorded in the same spectral range in reflectance mode, processed with Kramers-Kronig transformation to extract absorbance information, and represented as Gram-Schmidt integral in a pseudo-color representation.