I cannot link the article cause it's in italian!
It was a scientific experiment for children. It was about boiling a red cabbage to extract the anthocyanin pigment, then using this juice adding in different containers different substances such as vinegar, citric acid, or baking soda to see how the color of the pigment changes reacting to different PH values.
I know about hydrangea but it's the opposite. Wondering now what colors hydrangeas.
