Physico-chemical characterisation of the fraction of silver (nano)particles in pristine food additive E174 and in E174-containing confectionery. Issue 11 (1st November 2020)

• Record Type: Journal Article
• Authors: De Vos, Sandra; Waegeneers, Nadia; Verleysen, Eveline; Smeets, Karen; Mast, Jan
• Is Part Of: Food additives & contaminants. Volume 37:Issue 11(2020)
• Page Start: 1831
• Page End: 1846
• Publication Date: 2020-11-01
• Subjects: E174 -- silver -- particle size distribution -- TEM -- spICP-MS -- food additive; Food additives -- Periodicals; Food contamination -- Periodicals; 664.06
• DOI: 10.1080/19440049.2020.1809719
• Languages: English
• ISSNs: 1944-0049

Abstract

ABSTRACT: Silver (E174) is authorised as a food additive in the EU. The unknown particle size distribution of E174 is a specific concern for the E174 risk assessment. This study characterised the fraction of silver (nano)particles in 10 commercially available pristine E174 food additives and 10 E174-containing products by transmission electron microscopy (TEM) and single-particle inductively coupled plasma-mass spectrometry (spICP-MS). TEM analysis showed that all samples contained micrometre-sized flakes and also a fraction of (nano)particles. Energy-dispersive X-ray spectroscopy (EDX) and electron diffraction confirmed that the (nano)particles and micrometre-sized flakes consisted of silver. A higher amount of (nano)particles was observed in the products than in the food additives. In addition, the surface of the micrometre-sized flakes was rougher in products. The median of the minimum external dimension, assessed as minimal Feret diameter, of the fraction of (nano)particles determined by quantitative TEM analysis was 11 ± 4 nm and 18 ± 7 nm (overall mean ± standard deviation), for food additives and products, respectively. Similar size distributions were obtained by spICP-MS and TEM, considering the limit of detection of spICP-MS. The median of the equivalent spherical diameter of the fraction of (nano)particles determined by spICP-MS was 19 ± 4 nm and 21 ± 2 nm (overall mean ± standard deviation), for food additives and products, respectively. In all samples, independent of the choice of technique, the nano-sized particles represented more than 97% (by number) of the silver particles, even though the largest mass of silver was present as flakes. GRAPHICAL ABSTRACT: uf0001