Experiment 5: Plastic Milk

Ok, I love chemistry! I think is is so fun, and educational, when you can see with your own two eyes some substance radically change. In this experiment you can change a glass of milk into a plastic! (no joke!)

Supplies:

• 1 glass of full cream milk (I also suggest doing this with a variety of creams and milks if you can afford it - whipping cream, whole milk, etc, to see how it affects the results)
•  vinegar
• eye dropper
• wooden/plastic spoon
• microwave (or a bowl of freshly boiled water)

Process:

1. fill a glass about 3/4 of the way with the whole cream milk
2. microwave the glass for about 1 minute until milk is warm
3. Fill the eye dropper with vinegar
4. stir milk with spoon as you slowly add the vinegar
5. Hold your hand over a sink (MAKE SURE THE MILK ISN'T TOO HOT!) pour the 'milk' over your hand, catching the plastic!

Explanation:
The cream in the milk contains a chemical called casein. When you add the vinegar, the casein separates from the rest of the milk. The molecules on casein are loosely bonded together in a chain, making form on plastic! Casein is a bonding protein found in many foods that contain Phosphoric Acid. It really is also included in may products like plastic, paint, etc. Therefore, it can be found in two forms: edible and technical. Casein is similar to salt in that it doesn't change form when added to a substance. I this experiment we can see that, as we are just separating those molecules from the rest of the molecules in the milk. Casein is a protein and acts as a binding agent. So it is an important part of making cheese and yogurt. On a side note: there have been studies that show a link in adverse effects of casein in those with autism. Many with autism have food sensitivities, similar to allergies. So families will avoid dairy, thinking they are avoiding the allergy, not realizing it is the casein (found in various other foods) that might be the culprit.