Assesing the behaviour of particulate/nanoparticulate form of E171 (TiO2) food additive in colored chocolate candies before and after in vitro oral ingestion by spICP-MS, TEM and cellular in vitro models

Potential risk of nanoparticles present in food additives should be assessed. Although food-grade additive E171 (TiO2) has been banned by European Union due to the potential occurrence of nanometric TiO2, it is still present in stock products and permitted in other countries. TiO2 (nano)particles from the outer coating of colored chocolate candies were determined by TEM (Transmission Electron Microscopy), ICP-MS (Inductively Coupled Plasma Mass Spectrometry) and spICP-MS (Single-Particle-ICP-MS). Total titanium content was in the range of 1219 ± 83 µg g-1, except for brown and white candies. Percentage of TiO2 particles bellow 100 nm was under 25% regardless the color, with most frequent size between 120 and 160 nm. In vitro gastrointestinal assays reveal differences in bioaccessibility percentages between whole candy (14%) or aqueous extracts of the coating of candy (37%). More than 90% of bioaccessible titanium was found in particulate form. Caco-2 cells viability decreased around 65% after 24 h exposed to intestinal fraction.