Q.1 Is it possible to use one’s tongue as a subatomic particle detector?
Q.2 If so, would that be a good idea?
According to Professor Stefan Frings,
of the Frings Group at Heidelberg University Institute of Zoology,
Heidelberg, Germany, it looks as though the answer to both questions is
‘Yes’.
He provides a general overview of such discoveries, in Proceedings of the National Academy of 
Sciences of the United States of America,
PNAS December 2010 107 (51) 21955-21956. Drawing attention to the fact
that the ability to detect ‘sour’ tastes is one of the least
well-understood gustatory talents.
But progress has recently been made,
and the current view is that the detection of sour tastes is linked to
the presence of hydrogen ions in the food. Since a normal hydrogen atom
is composed of one proton and one electron, a hydrogen ion (missing its
electron) can simply be thought-of as a free proton.
Thus the
sour-specific cells of mammalian tongues are, in effect, proton
detectors. And this is an important, perhaps even life-saving skill –
for sometimes, sour (acidic) foods might be dangerous to eat.
“When an animal eats, there is a brief but absolutely
vital period during which it must reach a decision as to what to do with
the food in its mouth: swallow it or spit it out.”
“Fortunately, the sense of taste has evolved to stand
sentinel over the digestive system. It provides last-moment information
on the suitability of food, and it enables the animal to come to an
almost binary decision: take it! or get rid of it!.”
The paper can be found here : The sour taste of a proton current.