CONCEPT 24: GREEN VEGETABLES LIKE IT HOT--THEN COLD Flashcards
Where do green vegetables get their bright color from?
Chlorophyll
Chlorophyll
Any of a group of green pigments found in photosynthetic organisms.
What does the complex molecule Chlorophyll contain at its center?
Magnesium ion
What happens to chlorophyll’s magnesium ion when it’s heated? What does this produce?
It loses the magnesium ion, resulting in a dull, olive-green hue–familiar to all of us who have eaten drab stalks of broccoli.
The process of color change is accelerated in the presence of what?
Acids
Do acids occur naturally in plants?
Yes
What is hard water?
Water that contains an appreciable quantity of dissolved minerals (like calcium and magnesium).
What is soft water?
Treated water in which the only ion is sodium.
Is rainwater soft or hard?
As rainwater falls, it is naturally soft. However, as water makes its way through the ground and into our waterways, it picks up minerals like chalk, lime and mostly calcium and magnesium.
Does hard water affect acid based dressings or boiled vegetables color?
Yes, it affects both.
What do acids do to chlorophyll?
Acids release hydrogen ions, which actually come in and replace chlorphyll’s magnesium ions, a change that produces a dull colored molecule called pheophytin.
How does a home cook get around boiling vegetables in hard water?
Cook fast and in order to soften texture but not compromise appearance–blanching is the key.
Should you use a small or large amount of water when blanching? Why?
A large amount will ensure the temperature doesn’t drop too much and vegetables cook rapidly.
Cooking quickly in a pot of boiling, salted water.
Blanching
Why is salt added to blanching?
Salt weakens pectin, helping to speed the softening of vegetables before chlorophyll has time to change.
Why aren’t raw vegetables bright green before blanching?
In raw vegetables, the pockets of air in the plant refract, and therefore dim, the color of chlorophyll.
How does a quick dip create a greener vegetable?
As soon as raw vegetables hit boiling water, some of the air contained between their cells expands and bubbles off, bringing the cell walls closer together and causing plant tissue to become more transparent, producing a brighter green color.
Why do we shock vegetables in ice water after blanching?
Abruptly halts the cooking process, preventing any further transformation of the chlorophyll.
TEST KITCHEN: BROCCOLI GIVEN AND ICE BATH VS NONE
After three minutes in the ice bath the broccoli was firmer with brighter color, the other was mushy and olive drab.
Color change in green vegetables after blanching.
Muted green to emerald green.
