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Silver Embedded Plastic Packaging can Form Harmful Nanoparticles in Foods

Antimicrobial packaging is created to prolong the shelf life and ensure the safety of foods and beverages. But there is a concern regarding the leaching of possibly detrimental materials, like silver nanoparticles, from these kinds of containers into consumables.

Large aggregations of silver nanoparticles form when dissolved silver is added to a sugary soft drink. Image Credit: Adapted from ACS Applied Materials & Interfaces 2021, DOI: 10.1021/acsami.0c17867.

Scientists have now described in ACS Applied Materials & Interfaces that silver combined in an antimicrobial plastic can leach from the material and develop nanoparticles in foods and beverages, specifically in sweet and sugary foods.

A few polymers that contain nanocomposites or nanoparticles can retard the growth of microorganisms that cause foodborne illness and spoilage of beverages and foods.

At present, these polymers are not approved for use in packaging in the United States, but scientists are examining several kinds of nanoparticle-embedded polymers that could be integrated into containers in the future.

Previous studies have demonstrated that a few of these polymers can release nanoparticles, ions and dissolved compounds into water-based food simulants. However, until now, not much is known regarding how such packaging might interact with real foods and beverages.

Certain sugar compounds, which are essential food ingredients, are more effective at transforming silver ions into possibly detrimental nanoparticles, and could further be ingested by humans.

Hence, Timothy Duncan and collaborators wished to notice how the complicated ingredients in sugary foods and beverages affected the development of such nanoparticles, both when exposed directly to dissolved silver and when they are stored within silver-laced packaging.

To investigate whether dissolved silver gets accumulated in complex edible mixtures, the team added silver into liquid foods and beverages, such as milk, soda, juices, yogurt, naturally and artificially sweetened solutions and starch-based slurry.

The mixtures were incubated at 104°F for about 10 days or more, thereby simulating long-term storage in packaging material. Detection of nanostructures was done at two silver concentrations, one at the scale anticipated from polymer-contact leaching, and the other at an unrealistically high concentration, enabling the team to track nanoparticle formation with the help of an eye.

Sugary liquids with fats, citrates and starches had the most nanoparticles, while acidic liquids originally developed silver aggregates that subsequently dissolved. In one more experiment, the scientists stored two sugary liquids and water in small packets of silver-laced polyethylene polymer at 104°F for 15 days.

There was a first release of dissolved silver from the polymer surface, but only the sugary solutions sustained additional leaching and the formation of nanoparticles. The team concluded that silver nanoparticle dietary exposure is feasible from sweetened foods and beverages that are packaged in antimicrobial materials under conditions typical of long-standing storage.

This study was financially supported by the U.S. Food and Drug Administration and the Oak Ridge Institute for Science and Education.

Journal Reference:

Yang, T., et al. (2021) Food and Beverage Ingredients Induce the Formation of Silver Nanoparticles in Products Stored within Nanotechnology-Enabled Packaging. ACS Applied Materials & Interfaces. doi.org/10.1021/acsami.0c17867.

Source: https://www.acs.org/

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