Make Your Pie Fillings Glow in the Dark
The presence of quinine in tonic water means that when you expose it to ultraviolet light it will appear to glow! Jessica (aka @ThePieous) of the website Piescrapers has put this fun quality of quinine to good use.
Her larger-than-life pies that tower in very un-pie-like ways, and some of them now glow under black light. Jessica has cleverly come up with a simple recipe for edible, UV-reactive glowing tonic gel. She uses plain tonic water, sugar, salt, and agar-agar (plus some lemon juice for flavor) in a recipe that comes together quickly and tastes like citrus jelly.
The agar-agar turns the mixture into a gel that can be applied over the top layer of any pie filling, though Jessica recommends cherry or citrus flavors for the tastiest result. Once the gel sets after 30 minutes, voila! Glowing pies!