If you wanted to use something instead of tonic water (quinine) to make piping gel or candy glow, you could try vitamin B2 (riboflavin); see the link for info.
You should let people know you use this, in case they have issues with a vitamin, or possible overdosing, etc. I didn't research that, so check it out to be safe.
This company is working on some additives to make food glow in the dark, without using a blacklight.
Ha, that reminds me of a marketing project I had to do in high school. We had to create a new product. I made glowing toothpaste. We only had to write about it, but I actually took a tube of toothpaste and added some glow-in-the-dark paint to the toothpaste (no one was going to be using the toothpaste.)
Glow in the dark food, what will they think of next? I'm trying to imagine in what situation people would be eating in the dark!?