Sanshool
The molecule behind the numbing buzz of Sichuan pepper, felt as a vibration on lips and tongue.
Also: hydroxy-alpha-sanshool, numbing compound, tingle compound
Sanshool is the compound that makes Sichuan pepper tingle. It acts on touch-sensitive nerve fibres, and experiments suggest it makes them fire at about 50 vibrations per second, a frequency the brain reads as a buzzing sensation. This is not a taste, nor heat, but a physical feeling, unlike capsaicin. It occurs in Zanthoxylum fruits, including sansho in Japan and timur in Nepal, and in the Asian plant known as the toothache plant, used in some drinks. Sanshool is unstable in air and light, and degrades once ground. For the best tingle, buy whole husks, keep them sealed, and grind close to use.