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Krampf #461 Red Meat
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KRA-@aol.com
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Apr 10, 2006 08:56 PDT
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Robert Krampf's Experiment of the Week
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This Week's Experiment - #461 Red Meat
Greetings from home! After a very busy school year of travel, I finally
have a week off! Then two more weeks of FPL shows in Ft. Lauderdale and then I
launch into taping my new FCAT Science video series, to help Florida students
do better on the FCAT Science test.
This week's experiment came to me while I was preparing a roast. To try it,
you will need:
a piece of beef, such as a roast, some stew meat, etc.
a knife
First, look at the piece of meat. It should have a nice, red color. Now
cut the meat, and look at the inside. Instead of being red, it is probably a
darker, reddish brown. What is wrong? Is this a piece of old meat? Did
the butcher dip it or spray it with something to make it look fresher than it
is? Let's find out.
Put the piece of meat that you cut onto a plate or saucer and then put it
into the refrigerator. Do not leave it on the counter, or your cat will have it
for a snack. (Voice of experience talking.) After about 15 minutes, look
at it again.
The part that was dark has now turned bright red, just like the rest of the
outside. Cut the meat again, and again you will find that the inside is a
dark, reddish brown color. OK, so what is happening?
Many people think that the red color of fresh meat comes from blood.
Actually, the red color comes from a substance called myoglobin. Myoglobin is
related to hemoglobin, the part of your blood that carries oxygen. Myoglobin
also holds oxygen, but it holds that oxygen inside the muscle, keeping it ready
for when the muscle needs it for rapid movement. Your muscles use oxygen when
they move, and if they run out of oxygen, then your muscle starts to hurt
from overuse.
When the cow was killed, its heart stopped pumping blood to the muscles.
The oxygen in the myoglobin was used up, and it turned a dark color. When you
cut the meat, the myoglobin was exposed to air, allowing it to absorb oxygen
from the air and turn the bright red color. Myoglobin is also changed by
heat, which is why the meat changes to brown when you cook it.
Not all meat contains myoglobin. For example, the white meat of a chicken
breast is fast contracting muscle, which uses glycogen instead. Those muscles
are for sudden motion, such as bursting into flight when a predator
threatens. Without the myoglobin, the meat is white. The muscles of a chicken leg
are slow contracting muscle, which does use myoglobin, so you get dark meat.
Muscles that are used a lot, for walking or running need the myoglobin for
endurance. That is why ducks have all dark meat, since they fly long distances.
Have a wonder filled week.
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My calendar is now on-line. You can see a detailed calendar, with dates,
times, schools, etc. at http://www.krampf.com/m_tour.html
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From Robert Krampf's Science Education Company
PO Box 60982
Jacksonville, FL 32236-0982
904-388-6381
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