You can make edible ink by reducing almost any colorful, edible, water-based liquid. Slow simmering a natural liquid like fruit or vegetable juice lowers the water content and results in a darker and often more viscous fluid. This natural, low-moisture edible ink dries in a few seconds after it has been painted, stenciled or stamped onto food. Add a personalized message to a special dish by spelling it out using a few different colors of homemade edible ink.
Pour an edible liquid into a heavy-bottomed saucepan and cover with a lid. Try using prune juice, red wine, beet juice or concord grape juice to create dark, edible ink that will stand out.
Place the covered saucepan on a stove burner set to medium heat to bring it up to a boil. It will only take a couple minutes for 1 cup of water-based liquid to reach boiling temperatures and build up enough steam to make the lid rattle.
Reduce the heat to low and remove the saucepan's lid when the colorful liquid begins to boil.
Simmer and stir the liquid uncovered for 15 to 20 minutes, or until it reduces down to approximately 2 tbsp., or about 1/8 the original volume.
Remove the saucepan from the heat and pour the hot edible ink into a small, oven-safe bowl. A silicone spatula makes it easier to transfer every last drop.
Set the glass bowl on top of a bag of frozen vegetables or an ice pack inside the refrigerator and wait 15 minutes for it to cool completely.
Remove the cooled edible ink and apply it directly to the surface of a food item in a single thin coat. Allow 30 seconds of dry time before adding additional layers of edible ink or serving an inscribed dish.
Cover any bowl of unused edible ink with a piece of plastic wrap and return it to the refrigerator for up to two weeks.