On Food and Cooking

Terpene compounds are constructed from a
zigzag building block of five carbon atoms,
which turns out to be amazingly versatile and
can be combined, twisted, and decorated into
tens of thousands of different molecules.
Plants usually produce a mixture of defensive
terpenes. They are characteristic of the
needles and bark of coniferous trees, of citrus
fruits (p. 374), and of flowers, and provide
pine-like, citrusy, floral, leaf-like, and “fresh”
notes to the overall flavor of many herbs and
spices. As a family, terpenes tend to be
especially volatile and reactive. This means
that they’re often the first molecules to reach
the nose, and provide the initial impression of
these lighter, more ethereal notes. It also
means that they’re readily boiled off or
modified by even brief cooking, which is why
these fresh, light notes disappear. If desired,
they can be restored to a cooked dish by
adding a new dose of the herb or spice just
before serving.