Miss Kitty is a remarkable animal and just about the most lovable pet in the world. She purrs when she is happy, and WE would expect her to purr while she is enjoying a tasty meal. Some people claim that they have a cat that purrs over her dinner, but this is not likely. The soft purring music comes from a set of false vocal cords in the cat's throat. She uses her throat to swallow, just as you do, and you cannot talk and swallow at the same time.
A contented cat may purr before and after each mouthful. But she cannot purr while the food is going down her throat.