food through the air to irritate our nasal
passages as well as our mouth. The active
ingredients of chillis and black pepper
become significantly volatile only at high
temperatures, above about 140ºF/ 60ºC, which
is why roasting hot chillis or toasting
peppercorns can cause everyone in the kitchen
to start sneezing. But mustard and horseradish
and wasabi can get into the nose even at room
or mouth temperature. Theirs is a head-filling
hotness.
The pungency of mustards and their
relatives arises from the same chemical-
defense system used by their vegetable
relatives in the cabbage family (p. 321). The
plants store their irritant defenses, the
isothiocyanates, by combining them with a
sugar molecule. The storage form is not
irritating, but it does taste bitter. When their
cells are damaged, special enzymes reach the
storage form and break it apart, liberating the
irritant molecules (and at the same time
barry
(Barry)
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