Taste and smell

The tongue is covered in tiny bumps that hold taste receptors. Food has to dissolve in saliva before they can taste it: sweet, salty, sour and bitter (and, many scientists add, the savoury taste of meat broth). Smells are tiny particles in the air; breathed in, they reach smell receptors high inside the nose. Much of what we call a food's taste is really its smell, which is why food tastes flat with a blocked nose.