Fortified breakfast cereals contain elemental iron, an added mineral that helps consumers meet daily nutritional needs. This iron is not chemically bound within the food matrix; instead, it exists as tiny, separate metallic particles. Because this iron is magnetic, a simple demonstration using household items allows you to extract and visibly observe these metal filings. This experiment provides a hands-on look at food science and fortification.
Gathering Your Supplies
To successfully extract the iron, start with a highly fortified cereal, such as corn flakes or puffed rice. Check the nutrition label for a high percentage of the daily value for iron. You will need a strong magnet, as standard refrigerator magnets are usually not powerful enough. A small, rare-earth neodymium magnet is recommended because its intense magnetic field effectively draws out the iron powder.
Preparation Materials
For preparation and collection, you will need a blender, food processor, or a mortar and pestle to crush the cereal into a fine powder. Use a clear, resealable plastic bag or a sturdy plastic container as the vessel for the experiment. Finally, gather warm tap water to create a slurry and a piece of white paper or plastic wrap for viewing the collected iron.
Step-by-Step Iron Extraction
First, crush the cereal into the finest possible powder. Take about one cup of fortified cereal and use a blender or mortar and pestle to thoroughly grind it down, aiming for a consistency similar to flour. This action breaks the cereal matrix and frees the minute particles of metallic iron embedded within the flakes.
Next, transfer the fine cereal powder into the plastic bag or container and add approximately two cups of warm water. Seal the container tightly, then gently mix the contents to create a thin slurry. The warm water helps dissolve the cereal, separating the iron particles and allowing them to move freely within the liquid mixture.
Place the strong neodymium magnet against the outside surface of the container, near the bottom. Slowly drag the magnet along the outside wall, moving it upward toward a single spot just above the water line. The magnetic field will pull the free-floating, microscopic iron particles through the liquid to the inside surface of the container wall.
Hold the magnet steady in that spot for a few minutes, allowing the maximum amount of iron to accumulate. A small, dark, grayish-black smudge or cluster should form on the inside of the container wall, clinging directly to the spot where the magnet is held. This dark material is the collected iron powder.
To isolate the iron for closer inspection, carefully slide the magnet away from the container without disturbing the collected iron smudge. Place a piece of white paper or plastic wrap on a flat surface. Using the magnet again, gently scrape the collected iron filings from the container wall onto the paper for a clear view of the surprisingly metallic substance.
Understanding the Science of Fortification
The success of this experiment is due to the form of iron used for fortification. The iron added to many cereals is elemental iron, often labeled as “reduced iron” or “iron powder.” This pure, metallic form of the element is strongly attracted to a magnet. Elemental iron is intentionally added during manufacturing because it is inexpensive and does not react with the food, meaning it does not alter the cereal’s taste, color, or shelf life.
Elemental vs. Ionic Iron
In contrast, the iron naturally found in foods or supplements like ferrous sulfate is in an ionic form, where the iron atom has lost electrons, making it non-magnetic. Despite its metallic appearance, elemental iron is safe to consume and can be absorbed by the body. Once ingested, the strong acid in the stomach dissolves the tiny metal particles. This chemical reaction changes the elemental iron (Fe) into the ionic ferrous form, which the body’s digestive system absorbs and uses for functions like producing hemoglobin.