NanoAg@ - Physico-chemical characterization of the fraction of engineered nanomaterials in silver (E174) food additives in the context of risk assessment

Last updated on 14-12-2022 by Pierre Daubresse
Project duration:
December 1, 2016
December 31, 2017

In short

E174 is a food additive approved by the European Commission which can be used for the external coating of confectionery items, for decoration of chocolates and in liqueurs. Commercial suppliers distribute the E174 food additive in the form of powders and sheets. This project aims to develop a validated methodology for the screening, detection and physico-chemical characterisation of (nano)particles in food additive E174.

Project description

This work aims at a systematic and larger scale examination of silver (E174) food additives and food items containing silver, available on the market. Overall, the project will support the control (regulators), application (consumers) and implementation (producers) of EU Regulation 1169/2011 for nanomaterials in the approved silver food additive E174
Specific goals are:

  • to prepare a representative test material for the food additive E174,
  • to provide science-based data, filling identified knowledge gaps for the (re-) evaluation of E174 food additive in line with Regulation (EU) No 257/2010, to re-evaluate the approved food additives under the responsibility of the European Food Safety Authority (EFSA), based on analyses of pristine food additives E174 on the market and on food products containing the food additive E174,
  • to improve the guidelines for characterization of silver engineered nanomaterial (ENM) in food in a regulatory context based on this specific example.

Number-based size and shape distributions and particle concentrations will be provided together with measurement uncertainties assuring a quality of data in line with the requirements of the EC definition of NM and with international guidelines.
The detailed physico-chemical characterisation and the estimation of the concentration of specific nano-sized silver particles in the pristine E174 and in the food matrix are of such quality that they can serve to estimate the exposure to silver food additive taken up as food. Based on the results for E174, a generic approach can be formulated.


The approach to characterize the fraction of (nano)particles developed in the nanofood@ project was implemented to characterize silver (nano)particles in E174 food additives and in food products containing E174.

Within this study, the fraction of silver (nano) particles was characterised in ten commercially available pristine E174 food additives and in ten E174-containing food products by transmission electron microscopy (TEM) and single-particle inductively coupled plasma-mass spectrometry (spICP-MS). It showed that all samples contained micrometer-sized flakes and also a notable fraction of (nano)particles. In all samples, 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. Their median size was approximately 15 nm.

The method was further applied in the development and characterisation of a suitable reference material in an interlaboratory study in collaboration with the Joint Research Centre of the European Commission.

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