On Food and Cooking

they gave rise. Their primary
photosynthetic pigments are
chlorophylls, with smaller amounts of
carotenoids, and they store energy in the
form of starch.
Red algae — nori, dulse — are most
common in tropical and subtropical
waters. They owe their color to special
pigment-protein complexes that are
soluble in water and sensitive to heat: so
during cooking their color can change
quite strikingly from red to green. Red
algae store their energy in a distinctive
form of starch, and also produce large
quantities of the sugar galactose and
chains made up from it, which give us
the gelling agents agar-agar and
carrageenan.
Brown algae — kelp, wakame —
dominate temperate waters and
supplement their chlorophyll with a
group of carotenoid pigments, notably