Body & HealthFact
Chilli heat isn't a taste – it's a false alarm.
The TRPV1 receptor on pain nerves opens above about 43 degrees Celsius – and equally to capsaicin from chilli or to acid. So your brain gets a "hot" signal although nothing in the tissue heats up. With prolonged contact the receptor desensitises, which is why capsaicin can also numb.
Useful: Pungency belongs to the pain system, not to the five taste qualities.
Source: en.wikipedia.org