Mother will chew her food excessively. It does not matter what it is, meat, vegetables, mashed potatoes. etc. We never noticed her doing this in years past, but she really makes a production of it. There is nothing wrong with her teeth, we grind her meat. She even chews applesauce. Is this an OCD oddity common with dementia? She had even picked up other irritating quirks I won't get into. If you ask her why she does this she gets defensive, often raising her voice.
I wouldn't ask your mom about this anymore if asking her irritates her. She's not hurting anything and while it may bug you it's harmless behavior. And it's behavior that you definitely can't change. Dementia and Alzheimer's are characterized by all kinds of quirky, weird behavior that we don't understand. Trying to understand it or trying to get an explanation for it will drive us crazy in the process. Unless it's harmful behavior it's easier to just let someone be.
its like, " i said meh, what dont you understand about meh ? " .
Not trying to be nasty, but funny, about a situation that is sad, infuriating and frustrating. Good luck.