On Food and Cooking

seaweeds have a characteristic iodine note
(iodooctane) as well as a hay-like one (from
the terpene cubenol). A few, notably species
of Dictyopteris used as flavorings in Hawaii,
have spicy aroma compounds that are
apparently reproductive signals. Some browns
are noticeably astringent thanks to the
presence of tannin-like phenolic compounds,
which in the dried seaweed form brown-black
complexes (phycophaeins).
Prolonged cooking in liquid tends to
accentuate fishy aromas, so often seaweeds
are cooked only briefly. The first step in
making the Japanese soup base dashi, for
example, is to start dried brown kelp kombu
in cold water, bring it just to the boil, then
remove the kombu, leaving behind mainly its
savory soluble minerals and amino acids.
Because flavorsome minerals and amino acids
crystallize on and in dried seaweeds, they
contribute more when they’re left unwashed,
and if thick, when scored with a knife to