A.,
I would contact your local early intervention system (called Infants and Toddlers here in Baltimore Co., MD) and ask for an evaluation from an occupational therapist. If they will not see you based on your own observation, ask your pediatrician to give a referral. It is a free service, and the therapist will come to your home until a child turns three.
The reason I suggest the OT is that it sounds like your daughter might either be having trouble chewing, moving the food around in her mouth, or might have low-tone and need more food in her mouth in order to really feel it in there. If any of these is the case, she may need some therapy, all of which is kept pretty fun at their age; my own 27-month-old daughter has benefitted tremendously from the OT.
Best wishes in solving this problem. Though she may be doing it for attention, I would get her evaluated to rule out an oral-motor issue.
Take care.