Raman Markers of Toxic Nanofraction in Anatase TiO2 Micropowder Used as E171 Food Additive

Titanium dioxide (TiO2) micropowders widely used in modern food industry may contain particles in highly-toxic nanoform. Unlike micrometer-sized crystals, which cannot penetrate cell membranes, TiO2 nanofraction causes the liver function damage, intestinal inflammatory response, and oxidative metabolism imbalance. In this study, we demonstrate the possibility of utilizing Raman spectroscopy for fast detection of nanofractions against the background of anatase TiO2 micropowders. The results reveal that the presence of nanofractions leads to the appearance of several physically-grounded features in Raman spectra of TiO2 associated with the weakening of the selection rules for first-order scattering processes, the size-related frequency shift of Raman-active vibrations, and the enhanced contribution of Raman processes related to the surface states. In combination with standard microfiltration methods, these Raman markers provide a simple method for express control of highly-toxic nanofractions in TiO2 micropowders used in the food industry.