Karkadэ. I found chemistry
When brewed hibiscus first passes into solution (in other words, is extracted) dye. In a neutral environment, it has a blue color. Then, from the colors extracted acid, which changes the color of dye. Soda in solution creates a basic environment. In basic medium, the dye becomes dark blue. Adding vinegar again creates an acidic environment, and color is red.
As in the chemical substance is called altering the color in the presence of acids or bases?