Lemon Sherbet

I'm trying to remember a book that I read as a child and I'm hoping someone can help me.

The only thing I remember is someone or some group of people could read minds, and so this other group of children or people would concentrate on orange sherbet (I think?) so their mind couldn't be read. One character said she would focus on lemon sherbet because she liked it better.

This is a long shot. I can't remember anything else about this book. If this sounds familiar to anyone, please let me know – Thank you!