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

Jun-Hee Lee,Ah-Hyun Jo,Ke Luo,Ji-Su Ko,Young-Rok Kim,Sang-Mook You

doi:10.3390/nano11020532

Abstract

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 SiO2 from food without altering the physicochemical property of SiO2 particles is of great need to accurately monitor its characteristics. Here, we report on an effective magnetic separation method to extract food additive SiO2 from food by utilizing a diatom-originated peptide with a specific affinity to SiO2 particles. The affinity-based magnetic separation was found to be specific to SiO2 particles over other types of inorganic food additives such as titanium dioxide and zinc oxide. The size and morphology of SiO2 were shown to not be affected by the extraction processes. This method was successfully applied to extract and characterize the food additive SiO2 from six different types of commercial food.

Highlights

The amorphous form of silicon dioxide, a synthetic amorphous silica (SAS), is authorized as a food additive (E551) in many countries including the European Union andU.S [1]
Silaffin was first discovered in the cell wall of a diatom made of amorphous hydrated silicon dioxide and has been shown to remain permanently associated within the silica structure of the diatom (Figure 1a)
The T8 domain consisting of 36-amino acid was reported to show sufficient affinity to the silicon dioxide cell walls of the diatom [26,27,28,29,30]

Summary

Introduction

The amorphous form of silicon dioxide, a synthetic amorphous silica (SAS), is authorized as a food additive (E551) in many countries including the European Union and. Extraction or separation of nanoscale food additives such as synthetic amorphous silica from food is challenging because food is comprised of a range of complicated matrices including carbohydrates, fats, proteins, and various salts [13]. These food components should be removed for the accurate analysis of inorganic food additives present in processed food. The harsh digestion reaction accompanied by extended treatment with strong acids and an intense heating process would affect the morphology and size of the constituent particles, which would distort the actual form of SiO2 particles present in food. The magnetic separation method developed in this study was successfully applied to extract SiO2 particles from commercial foods that are sold in the market for further characterization

Materials

Expression and Purification of MBP-SBP

Binding Assay of MBP-SBP for Food Additive SiO2

Characterization of Separated Silica Nanoparticles

Results and Discussion

Magnetic Separation of SiO2 in the Presence of Food Components