If you came to our Science Spectacular you would have seen the chemistry lab out on the veranda. I found a few spare minutes to go and have a chat with the chemists – Aaron, Stephanie and Tessa – and have a play with one of their experiments.
In this video you can see a tray of milk with swirls of food colouring.
[youtube height=”480″ width=”853″]https://youtu.be/fzChxWr-_hk[/youtube]
[Video audio: Background music and talking.]
Milk contains four main components: water, fats, proteins and sugars. The fats are unable to dissolve in the water, instead forming an emulsion (this is why milk is cloudy white).
You can see that the food colouring doesn’t disperse and mix through the milk like it would do it water. The real magic happens when a drop of detergent is added to the mixture (by immersing a soapy cotton bud). The detergent causes the proteins in milk to separate from the rest of the components and the food colouring acts as though it has seen a ghost.
Yay, science!