FT-IR spectroscopy and microspectroscopy of ancient egyptian embalmed heads from the Museum of Anthropology and Ethnography of the University of Turin

Fourier Transform Infrared (FT-IR) spectroscopy and microspectroscopy were used to gain insight into the state of preservation of the skin of two Egyptian dynastic embalmed heads (VI-XI Dynasty) and one Predynastic mummy. The mummies came from the necropoles of Asiut and Gebelein (Upper Egypt), and are curated at the Museum of Anthropology and Ethnography of the University of Turin. The state of preservation was inferred from the biochemical composition of the skin, in particular from the secondary structure of the proteins. The secondary structure of the skin protein was investigated by studying the position and shape of the Amide I band, analyzed by means of self-deconvolution techniques. The increase in the b-sheet relative amount in the protein conformation of the mummified tissues with respect to the modern skin, was correlated with aging processes of collagen and keratins, the most abundant proteins in the skin. The steps of the degradation processes are hypothesized and described, and the differences in the recorded state of degradation were ascribed to the diverse mummification procedures undergone by the studied human remains. Other non-skin-derived features in the IR micro spectra of the embalmed specimens were detected and identified either as embalming materials or microbial attack traces.