you ever notice when vegetables are cooked they brighten up? Spinach becomes a
bight green, then if it's cooked too long it seems to turn grey. What is behind
this color change? How can we keep the color? Why does the color change occur?
Vegetables with Color:
and Vegetables owe their colors to various plant pigments. Spinach is green because
it contains the pigment chlorophyll.Chlorophyll is a chlorin pigment, which is
structurally similar to the iron-containing porphyrin compound known as heme.
At the center of the chlorin ring is a magnesium ion. The sidechains vary somewhat
between the different forms of chlorophyll found in different organisms. Chlorophyll
a is present in all green plants, but chlorophylls b and c also occur in various
groups. They also contain carotenoids, determining the color of the plant All
green plants contains chlorophyll a, and most vegetables that we eat contain both
chlorophyll a and chlorophyll b, some vegetables contain particularly high amounts
of total chlorophyll. Best studied of all the vegetables is spinach (Spinacia
oleracea in the Latin scientific name), with this vegetable containing about 300-600
milligrams per ounce.
happens when chlorophyll is heated?
has a chemical structure (containing a porphyrin ring) that is quite similar to
a chemical structure found within our red blood cells. Chlorophyll however contains
a magnesium atom in its center while heme contains an iron atom. When plants are
heated and/or exposed to acid (and when green vegetables are cooked and/or exposed
to acid), the magnesium gets removed from the center of this ring structure and
replaced by an atom of hydrogen. This results in a change from chlorophyll to
pheophytin. Chlorophyll a gets turned into a molecule called pheophytin a, and
the chlorophyll b gets turned into pheophytin b. The color of the vegetable changes
from bright green to olive-gray. (The pheophytin provides a green-gray color,
and the pheophytin b provides an olive-green color).
can be used to slow the change in color?
effect do acids and bases have on the color of different vegetables?
effect do different cooking methods have on changes in color?
effect does Vitamin C have on changes in color?
on this project!
chromatography during different stages of cooking. This will identify the changes
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