By Travis West, Extension Educator, 4-H Youth Development, Vinton County
Milk is produced by all mammals to raise their young, but we also consume it as an animal product coming from cattle, sheep, or goats. Milk is mostly water but also contained vitamins, minerals, proteins, and fat. You don’t just add water to dilute your whole milk to skim milk. You need a way to remove those fat molecules to change whole milk to skim milk (sometimes call fat-free). We have a way to see these fat molecules in motion – it will convince you they exist!
Magic Colored Milk Science Project
If you add food coloring to milk, not much happens, but it only takes one simple ingredient to turn the milk into a swirling color wheel. Here is what you do:
Magic Milk Materials
- 2% or whole milk
- food coloring
- dishwashing liquid
- cotton swab
Magic Milk Instructions
- Pour enough milk onto a plate to cover the bottom.
- Drop food coloring onto the milk.
- Dip a cotton swab in dishwashing detergent liquid.
- Touch the coated swab to the milk in the center of the plate.
- Don’t stir the milk; it isn’t necessary. The colors will swirl on their own as soon as the detergent contacts the liquid.
How It Works
Milk consists of many different molecules, including fat, protein, sugars, vitamins, and minerals. If you just touch a clean cotton swab to the milk (try it!), not much will happen. The cotton is absorbent, so you create a current in the milk, but you don’t see anything dramatic happen.
When you introduce detergent to the milk, several things happen at once. The detergent lowers the surface tension of the liquid, so the food coloring is free to flow throughout the milk. The detergent binds with the fat molecules in the milk, altering the shape of those molecules and setting them in motion. The reaction between the detergent and the fat forms micelles, which is how detergent helps lift grease off of dirty dishes. As the micelles form, pigments in the food coloring get pushed around. Eventually, equilibrium is reached, but the swirling of the colors continues for quite a while before stopping.
For more information contact Travis West, email@example.com.
Peer-Reviewed: Sally McClaskey, OSU Extension Program Manager, Education & Marketing. She develops and directs educational programs at the Nationwide & Ohio Farm Bureau 4-H Center.