Silver is well known to have antimicrobial properties. For this reason, silver nanoparticles are currently used in a range of packaging and storage products to increase the shelf life of food. There are, however, concerns about potential transfer of the nanoparticles into the food, especially as the toxicity of silver nanoparticles is not well understood. This has led to some food packaging products being banned from the market in certain countries, at least temporarily. A number of studies have previously examined the total amount of silver released into food from food storage containers. Now, Aiga Mackevica and colleagues at the Technical University of Denmark have examined the release of silver from storage products in terms of particle size, number concentration, and transfer rate, as well as total amount.
The researchers examined four products (two storage boxes and two bags) that were placed in contact with three different food simulants (Milli-Q water, 90% ethanol and 3% acetic acid) and left for 10 days. They then used mass spectrometry, as well as a range of microscopy techniques, to analyse the transfer of material. The total amount of silver found in the food simulants was less than the limit fixed by food authorities such as the European Food Safety Authority. However, the study showed that the silver can be transferred in the form of nanoparticles and the largest nanoparticles were found when using acetic acid as the simulant. The work highlights the need for further research into the toxicity of nanoparticles before a clearer picture on the use of silver in packaging can be formed.
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Pulizzi, F. Nanotechnology in food: Silver-lined packaging. Nature Nanotech (2016). https://doi.org/10.1038/nnano.2016.11