How often does she do this? How often are you finding that you are saying 'no' to her, and in what contexts besides the pears?
I think before ignoring her behaviour I might first of all start looking more into why she is doing it, how often etc. I don't tend to think that babies do things for no reason, and since they can't 'tell' us with words that something is wrong, their behavior is the only thing they've got. Ignoring them kinda seems like it should be more of a last resort to me.
If it were me, I'd start to wonder if the 'yes' to 'no' ratio was as it should be. In other words, I try to say 'yes' more often than I say 'no' to a young child or baby, so that they are rewarded for 'seeking' behavior and learn that they have a certain say in their own environment, certain control over what they do etc. I try to not even say 'no' much, unless its absolutely necessary - wherever possible choosing something like: 'oh look, we're out of pears' in a cheerful voice - wow, you've eaten a heck of a lot of those pears, haven't you, what a good eater you are!! What a clever girl. Etc., etc.
Could your daughter be a bit bored at all?
A lot of what babies of this age tend to do is try and learn by doing - making messes, finding out what things feel, sound and taste like etc... They don't tend to have any hidden agendas, and they don't have any ability to manipulate. They also have very little impulse control.
I personally feel that there is a lot of pressure around these days to keep baby clean all the time, keep the house clean etc., etc., which sometimes can result in us saying 'no' more to their innocent seeking behaviors designed to teach them more about their world (which often seems very weird and wonderful I'm sure). This is something they find extremely frustrating, especially if they can't yet communicate, and/or if they are a bit bored.
In that regard, the suggestion about sign language is an excellent one - if she can tell you whether she'd prefer apples or bananas etc, then she may feel a bit less frustrated.
Good luck!