Fate Determination and Characterization of Food Additive Silicon Dioxide and Titanium Dioxide in Commercial Foods

Background: Silicon dioxide (SiO2) and titanium dioxide (TiO2) are ones of the most widely used food additives as an anti-caking and a coloring agent, respectively, in the food industry. Understanding particle, aggregate, or ionic fates of two additives in commercial products is of importance to predict their potential toxicity. Methods: Triton X-114 (TX-114)-based cloud point extraction (CPE) methods for two additives were optimized in food matrices. Their particle or ionic fates in various commercial foods were determined by the CPE, and the physico-chemical properties of separated particles were further characterized. Results: SiO2 and TiO2 were primarily present as particle forms without changes in constituent particle size, size distribution, and crystalline phase. The maximum solubilities of SiO2 and TiO2 were 5.5% and 0.9%, respectively, depending on food matrix type, supporting their major particle fates in complex food matrices. Conclusions: These findings will provide basic information about the fates and safety aspects of SiO2 and TiO2 additives in commercial processed foods.