By Harold McGee
The Chinese spice known as Sichuan pepper and the Japanese sansho both offer a strange and interesting version of pungency. They come from two small trees in the citrus family sometimes called “prickly ash.” Sichuan pepper trees are Zanthoxylum simulans or Z. bungeanum, and sansho trees are Zanthoxylum piperitum. (Xanthoxylum is another spelling.) The spices are the small dried fruit rinds, which are aromatic with lemony citronellal and citronellol. The pungent compounds, the sanshools, are members of the same family as piperine from black pepper and capsaicin from chillis. But the sanshools aren’t simply pungent. They produce a strange, tingling, buzzing, numbing sensation that is something like the effect of carbonated drinks or of a mild electrical current (touching the terminals of a nine-volt battery to the tongue). San-shools appear to act on several different kinds of nerve endings at once, induce sensitivity to touch and cold in nerves that are ordinarily nonsensitive, and so perhaps cause a kind of general neurological confusion.