From a young age we are taught that iron is a nutrient that makes us strong. It is a vital component of haemoglobin, which is the substance in red blood cells that carries oxygen.
Since the 1940s, breakfast cereals have been fortified with a variety of vitamins and minerals, and today they represent one of the key ways that children meet their daily iron requirements. This is especially true for youngsters who otherwise have an unvaried and nutrient-poor diet.
Unlike iron that occurs naturally in meat and veg, the iron in cereals is added as a powder during production. Few people realise that it looks just like iron filings. Get hold of the strongest magnet you can find, then extract the iron from your cereal to see it with your own eyes.
You will need
- An iron-fortified breakfast cereal (make sure it’s light in colour so you can see the iron – we used a crisped rice cereal and a multigrain cereal)
- Rare earth magnet (these are extremely strong magnets, usually made from neodymium)
- A large, sealable transparent food bag (a zip-lock style bag is ideal)
- A rolling pin and clean surface
Rare earth magnets are incredibly powerful. Do not swallow. Do not allow young children to play with them.
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- Pour dry breakfast cereal onto a surface and crush into a powder with a rolling pin.
- Put your magnet into the cereal dust. Carefully lift the magnet and you should see that tiny pieces of cereal are gripping the magnet.
- Pour one to two bowlfuls of breakfast cereal into a transparent food bag. If the cereal hasn’t already been crushed, crunch it up with your hands. Pour in enough water to completely cover and saturate all the cereal.
- Seal the bag and squash all the pieces until it is a smooth consistency, like thin soup. Put the magnet on the surface and place the bag on top. Agitate the bag so the cereal has a chance to be near the magnet. Leave it to rest for an hour.
- Carefully lift the bag, taking care not to shake it, and raise the magnet to keep it touching the same spot on the bag. Look closely: you should now see a small patch of dark iron powder next to the magnet. Move the magnet across the surface of the bag to drag the iron particles around.
What’s going on?
The iron that is added to breakfast cereal is just like the iron that goes into metal screws and nails, and is strongly attracted by a magnet. Grinding and crushing the cereal into a liquid mixture frees the added iron particles from the cereal matrix, allowing them to move towards to the magnet.
Without fortification, many breakfast cereals would have little nutritional value. Cornflakes, for example, are milled, dried, toasted and squashed corn kernels with added sugar, salt and flavourings. They are devoid of most of the fibre and many other important nutrients that were originally present in the cereal seed.
Furthermore, the milk that we pour onto cereal can have an inhibitory effect on how much of this precious nutrient can be taken in by the body. All of which goes to show the importance of a varied and balanced diet.
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Stuart is a science and medical writer, presenter and educator. He is a trained medical doctor and qualified teacher, and a food scientist for the BBC’s Inside the Factory.