What a great idea! The big problem with using food juices for pigments as opposed to mineral pigment is one of color fading and changing with food colors. Adding it to gum arabic is something I hadn’t thought of. I like the chile idea alot, but I can see it not lasting too long or changing color within a short span of time. Sometimes that isn’t a bad thing though if longevity isn’t an issue. The colors that food like beets, onions and chiles make are wonderful. Yours truly, a former art student, Zataar.