Synthetic Ligand-Coated Starch Magnetic Microbeads for Selective Extraction of Food Additive Silicon Dioxide from Commercial Processed Food

The amorphous form of silicon dioxide has long been regarded as a safe food additive (E551) that is widely used in commercially processed food as an anticaking agent. However, starting with titanium dioxide, there have been growing safety concerns regarding to the use of nanoscale silicon dioxide particles in food as food additives. The size, morphology, and chemical properties of inorganic food materials are important parameters to determine its potential toxicity. Therefore, an effective means of extracting an intact form of SiO(2) from food without altering the physicochemical property of SiO(2) particles is of great need to accurately monitor its characteristics. Here, we report on an effective magnetic separation method to extract food additive SiO(2) from food by utilizing a diatom-originated peptide with a specific affinity to SiO(2) particles. The affinity-based magnetic separation was found to be specific to SiO(2) particles over other types of inorganic food additives such as titanium dioxide and zinc oxide. The size and morphology of SiO(2) were shown to not be affected by the extraction processes. This method was successfully applied to extract and characterize the food additive SiO(2) from six different types of commercial food.