In fact, in a 2013 paper, researchers rubbed the substance on volunteers' lips and then tapped their fingertips with devices that can vibrate at a variety of frequencies, asking them to say which frequency most resembled the throbbing caused by the peppercorn. Consistently the answer was about 50 Hz, which suggested to researchers that a certain type of nerve is responsible for the sensation, one that is sensitive to that particular frequency.

Spicy heat

Another “non-taste” taste is the burning of capsaicin, the molecule that gives hot peppers their kick. Capsaicin binds to a receptor on cells that detect temperature and cells that send messages of pain. The same receptor and related ones are activated by piperine, a compound in black pepper that you might shake on your eggs in the morning, and allyl isothiocynanate, the burning compound in mustard and radishes.

It feels hot when you eat these foods because the receptors they trigger are usually switched on at temperatures higher than 42C or by acid, presumably to warn us that whatever we've put in our mouths is bad news. However, capsaicin and other hot foods won't damage your tongue – eat as much as you want.