Is it true that food colouring will not dye milk until it is stirred in?

26 Jan

I once read that if you put a few drops of food colouring in milk it sinks to the bottom and stays there until the milk is moved (then it spreads through the milk to make it another colour). It’s never worked for me, is that because it was false or is there a way to make it work?

The theory is good, but in practice it only works with food colouring that is blue.

This is because when it’s blue, it’s feeling a bit down and melancholy and doesn’t feel like going out. It would rather sink out of sight and not mingle. Red wants to be on show, and yellow is full of energy and likes to move around, but blue just wants to stay out of the way.

What’s really interesting is to try using a shallow saucer of milk, and put colours in different places. (Notice how the blue has sunk out of sight but the red is all up in your face.)

Then you need to get a cotton bud (or Q-tip, if you’re not familiar with Empire terminology) and put some washing-up liquid on there.

I like to use this brand because it’s named after that R.E.M song and I end up singing it when I wash up.

Gently touch it to the centre of your dish and see what happens.

The reason this happens is because washing up liquid enzymes act like the antibodies in our immune system. They identify bad things, chase them down and eat them. White blood cells chase down infections, and detergents chase down dirt.

Against the white background, the washing up liquid detects the food colouring as dirt and chases it down trying to eat it. Obviously there is not enough detergent to get the job done and clean it all away so the result is the effect you see in your dish.

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Posted by on January 26, 2013 in How?, Science, What?


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