blue — and they’re altered by traces of
metals, so they are often the source of strange
off-colors in cooked foods (p. 281).
Red and Yellow Betains A fourth group of
plant pigments is the betains, which are only
found in a handful of distantly related species.
However, these include three popular and
vividly colored vegetables: beets and chard
(both varieties of the same species), amaranth,
and the prickly pear, the fruit of a cactus. The
betains (sometimes called betalains) are
complex nitrogen-containing molecules that
are otherwise similar to anthocyanins: they
are water-soluble, sensitive to heat and light,
and tend toward the blue in alkaline
conditions. There are about 50 red betains and
20 yellow betaxanthins, combinations of
which produce the almost fluorescent-looking
stem and vein colors of novelty chards. The
human body has a limited ability to
metabolize these molecules, so a large dose of