The Role of Pectins in the Body Image Formation on the Turin Shroud

UV-induced fluorescence (UVIF) data that were obtained in the 1978 investigation of the Turin Shroud, were recently revisited by Pellicori supporting different behavior of background, non-image, and body image areas. Based on the experimental literature results, the chemical nature of that difference is discussed here. Former enzymatic analysis using pectinase indicated the presence of pectic substances, but only for fibers extracted from the background non-image areas. On the other hand, the high content of pectins in the primary cell wall (PCW) of flax fibers is well documented. The PCW is a thin outermost layer of fibers of approximately 0.2 μm, which corresponds to the layer where the body image is seen. Pectins are easier oxidized and destroyed than cellulose, the main component of the linen. In the present paper, pectins from the PCW of the linen fibers are proposed to participate in the initial stage of body image formation on the Turin Shroud, although they have been destroyed in that process. To demonstrate the presence of pectins in the fibers from the Shroud, the results of Fourier Transform Infrared (FTIR) spectroscopy in attenuated total reflectance (ATR) mode obtained by Fanti for body image and non-image fibers have been compared. Analyzed spectra do not exclude the presence of pectins. Thus, participation of pectins can explain some unique properties of the Shroud image, i.e., superficiality of the body image and nonuniform distribution of its yellow color.