use of the pigment chlorophyll, which is responsible for
giving green vegetables their bright green color.
Between all of the plant cells are trapped tiny pockets of
gases that scatter light waves, partially obscuring your view
of the vegetable’s bright green pigments. As soon as you
plunge it into boiling water, though, those gases escape and
expand, and the unhindered view of its pigments makes the
vegetable appear suddenly much greener. At the same time,
an enemy from within—an enzyme called chlorophyllase—
is working to destroy the vibrant green color by altering the
shape of the chlorophyll. Chlorophyllase is most active at
temperatures below 170°F, and it is destroyed at around
190°F. That’s the reason why a large pot of water is
necessary. With a small pot of water, the vegetables spend
too much time under that 170°F cutoff, giving the
chlorophyllase a head start in dulling their appearance. With
large pots of boiling water that never drop below 190°F, the
chlorophyllase is rapidly destroyed before it has a chance to
get to work on the chlorophyll.
Even with the cholorphyllase out of commission, a
boiling green vegetable will eventually begin to turn drab as
heat causes irreversible changes in its structure. These
changes are exacerbated by acidic conditions—even a few
teaspoons of lemon juice or vinegar in a large pot of boiling
water can cause green vegetables to rapidly turn dull when
cooked in it. This is the second reason why vegetables
should be cooked in plenty of water. As they cook, they
release their naturally acidic contents into the cooking
medium, acidifying it and hastening browning. Using a
large volume of water dilutes this acidity. Similarly,
nandana
(Nandana)
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