nanoparticlesIn my recent blog post on food packaging material migration, I discussed some common contaminants found in food packaging and the analytical methods that can be used to detect them. LC/GC magazine recently published a great Q &A article with Dr. John Gilbert (registration required): Analytical Challenges in Measuring Migration from Food Contact Materials.

Today I’d like to get into a more specific area of food contact material analysis: nanoparticles.

Nanoparticles are between 1 and 100 nanometers (10−9 and 10−7 meters) in size, and have become part of food packaging technology due to their unique properties. Packaging containing nanoparticles can extend food’s shelf life, reduce the need for preservatives, and provide non-stick, easy-clean surfaces. Nanotechnology-enabled packaging usually falls into one of three classifications:

  • Improved packaging: Particles are mixed into the polymer matrix to improve gas barrier properties, temperature and humidity resistance of the packaging.
  • Active packaging: Particles interact directly with the food or the environment for better protection of the product. For example, silver nanoparticles are anti-microbial, with other materials being used as oxygen or UV scavengers.
  • Smart packaging: Particles detect biochemical or microbial changes in food, such as when pathogens or gases develop in a product due to the food spoiling.

 

Food Packaging that Contains Nanoparticles- 3 Examples

  • Glass bottles, such as beer bottles: Plastic mixed with clay nanoparticles helps make beer bottles more resistant to shattering, and also extends the beer’s viable storage time.
  • Plastic wrap and plastic sandwich bags: Nano-size copper and silver particles have antimicrobial properties, inhibiting growth of micro-organisms and helping keep food fresh for longer.
  • Plastic bottles: Nano titanium nitride is added to bottles used for water and soda to improve temperature and moisture stability.

 

Migration into Food

Studies have shown that nanoparticles can migrate from packaging into food. A food’s acidity can influence migration, with more acidic food causing more migration. Heating also increases migration, with microwave heating inducing more migration than heating in an oven or on a stove.

 

Possible Harmful Effects

Reducing chemicals to nanoparticle size can seriously alter their physical properties. For example, the lead found in pencils becomes stronger than steel when it is reduced to nano-size atomic clusters. The reactivity of many substances can change at the nano level, and not enough research has been done for scientists to fully understand the potential implications for human health.

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Research and Regulation

The detection and characterization of nanoparticles present scientists with unique challenges, as nanoparticles are invisible to the human eye. They are observable under optical microscopes only in liquid samples under certain conditions. In general, specialized techniques are required to see them.

The Project on Emerging Nanotechnologies keeps a list of nanotechnology-based consumer products. The database includes 118 products in the food and beverage category, with subcategories of Cooking, Food, Storage, and Supplements.

Food labeling regulations currently don’t require nanomaterials to be listed as an ingredient in food or in food packaging. In fact, there is a great deal of research still to be done regarding the particles’ effect on the human body. Studies have shown that nanoparticles are small enough to permeate biological membranes, including the blood-brain barrier, and can penetrate tiny capillaries throughout the body. Animal studies have shown potential toxicity of nanosilver for the liver, kidneys, and the immune system, but whether or not this toxicity affects humans in a similar way remains uncertain.

 

Additional Resources

For more information on nanoparticles in food contact material and migration of food packaging, visit these valuable resources.