Color Changing Ice Cream: Color changing ice cream is not new at all. There is a patent here which was filed in 2001 for a "Frozen dessert novelty which changes color". It describes the use of "red cabbage extract (anthocyanin)" to achieve the effect.
In 2014 a Spanish Man …
Spanish physicist, engineer, professor and ice cream lover Manuel Linares has together with a couple of colleagues created an ice cream that changes colors when it's licked—in a cone. Not content with the life of a physics professor, Linares signed up for training with Asociación Empresarial Naci... Read more
You could also make it at home with this guide.
https://www.instructables.com/Color-Changing-Ice-Cream/
There is an ice cream shop in New York City that sells this type of ice cream.
Already done! This physicist created an ice cream that changes color with every lick.
https://phys.org/news/2014-07-physicist-ice-cream.html