Reduced bioaccessibility of TiO2 (E 171) during puree soup digestion in a gastrointestinal tract simulated in vitro

E171 (TiO2- Ttitanium dioxide), a food colourant containing nano fractions, is one of the additives used e.g. in the food industry, whose consumption may have a negative impact on human health. In order to determine the ability of food products and intestinal lactic acid bacteria to interact with TiO2, we conducted in vitro "digestions" of a food matrix (meat/vegetable puree soup) using an advanced in vitro model of the "gastrointestinal tract". The "bioaccessibility" of TiO2 was simulated using microfiltration (0.2 mu m) of the post-digestive fluid. We observed changes in the content of TiO2 in the microfiltrates obtained at various stages of the in vitro digestions, dependent on the stage of the process. This result suggests that TiO2 interacts with food components and bacterial cells. Furthermore, scanning electron microscopy revealed visible morphological changes to bacterial cells in the presence of TiO2.