On Food and Cooking

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).
Sanshools 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