Re: why do banana taste more sweeter when it is mashed?

There are several possible explanations for your observation.  First,
bananas need to be fully ripe to mash well, and fully ripe bananas are
sweeter than firm bananas.  Another possible explanation is the tongue
tastes mostly liquid things; solids are not tasted well.  The taste buds 
are
on the tops and sides of "bumps" on the tongue called papillae and liquid
matter can touch these taste buds much better than solids.  A mashed banana
is much more liquid than a whole banana, so it touches many more taste buds
than a solid piece of banana.  These are reasons why I think the mashed
banana tastes sweeter than a whole banana.

Phyllis Stumbo
University of Iowa,
Iowa City, IA, USA