Why didn't the female titan and the bearded titan just (spoilers)

....eat Eren by chewing?


Anime and Manga spoilers below

I mean, with the bearded titan, it was weird how not only did he swallow Armin whole when most titans violently crunch their victims, but that he just swallowed Eden and only chomped his arm off. I know titans aren't exactly smart, but if he had just chewed Eden up, he would have been able to turn back into a human since Eren is a titan shifter.

With female titan, it's different, I know. She had a mission to acquire Eden by capturing him. And she didn't necessarily know he had the coordinate in him. But if she still devoured him then and there by chewing him up, it would have been over for humanity.