Described herein are nanoparticle silica Pickering emulsions comprising an aqueous suspension of colloidal silica mixed with a quaternary ammonium biocide. Additionally, the composition may include a small amount of organic solvent; such as methanol, ethanol, isopropanol, and mixtures thereof; wetting agents, such as a silicone-based wetting agent; and organic bases which act as solvent buffers, if it is desirable to raise the pH of the composition, such as monoethanolamine (MEA). The combination of nanoparticle silica and quaternary ammonium biocide provides food contact sanitization at less than 200 ppm of quaternary ammonium active.