Here’s a really simple and fun experiment to do at home: make glowing jelly (or jello, American friends)! The method is really easy – you’re just making jelly – but you do need some kind of UV light source to see the effects.
It’s a very simple idea: you make jelly but use a 1:1 mixture of plain ol’ water and tonic water (e.g. Canada Dry). Tonic water contains quinine which is naturally fluorescent and so the resultant jelly will glow under a UV light. Here’s what I did:
- Boil 100ml of water and mix with the jelly so it all dissolves.
- Top up with cold water up to 300ml.
- Add 300ml of tonic water.
- Mix it up really well and put it in the fridge.
Quinine glows a blue-ish colour under UV light so I used green jelly to maximise the effect. I’m assuming that the jelly acts as a kind of filter to the fluorescence, so using red jelly would probably result in a very poor glowing jelly. And nobody wants that. There was no blue jelly in the shop; not much blue food in general, actually.
Fluorescence occurs in some materials when they absorb high-energy light photons and then re-emit that energy as lower-energy photons. In this case, the quinine is absorbing UV photons and re-emitting them as visible light (UV light is higher-energy than optical light).
The results were pretty much awesome. You can see our glowing green jelly above. It tasted great too. Lime turned out to be a good flavour to accompany the tonic water, which would normally have a bitter taste. The kids gobbled it up – under the glow of the UV lamp.
This project was really quick and easy and the kids loved it! I think there may be glowing jelly – and maybe other glowing foods – at Halloween this year.