Download The Chemistry of Burgers

The Chemistry of Burgers
https://archives.nbclearn.com/portal/site/k-12/browse/?cuecard=52174
General Information
Source:
Creator:
NBC Learn
Al Roker
Resource Type:
Copyright:
Event Date:
Air/Publish Date:
02/09/2011
02/09/2011
Copyright Date:
Clip Length
Video Science Explainer
NBCUniversal Media,
LLC.
2011
00:06:15
Description
This NBC Learn video, one in a 6-part "Cheeseburger Chemistry" series, uses the cooking of hamburgers
to explain the structure of myoglobin, its role in making red meat red, the effects of heat on myoglobin's
structure and meat's color, and the Maillard -- or browning -- reaction.
Keywords
Burger, Hamburger, Ground Beef, Red Meat, Myoglobin, Protein, Amino Acid, Helix, Double Helix, Iron
, Atom, Denaturing, Denature, Heat, Temperature, Reaction, Maillard, Browning, Sugar, Carbohydrates,
Muscle, Tissue, Kent Kirshenbaum, New York University, Julie Yu, The Exploratorium, San Francisco,
John Kendrew, Max Perutz, Nobel Prize in Chemistry, National Science Foundation, Cheeseburger,
Cheeseburger Chemistry, Chemistry of Food, Food, Hamburg, Germany
Citation
© 2008-2015 NBCUniversal Media, LLC. All Rights Reserved.
Page 1 of 4
MLA
"The Chemistry of Burgers." Al Roker, correspondent. NBC Learn. NBCUniversal Media. 9 Feb. 2011.
NBC Learn. Web. 9 January 2016
APA
Roker, A. (Reporter). 2011, February 9. The Chemistry of Burgers. [Television series episode]. NBC
Learn. Retrieved from https://archives.nbclearn.com/portal/site/k-12/browse/?cuecard=52174
CHICAGO MANUAL OF STYLE
"The Chemistry of Burgers" NBC Learn, New York, NY: NBC Universal, 02/09/2011. Accessed Sat Jan
9 2016 from NBC Learn: https://archives.nbclearn.com/portal/site/k-12/browse/?cuecard=52174
Transcript
The Chemistry of Burgers
AL ROKER, reporting:
The burger part of a cheeseburger is short for hamburger, which is what Americans call a cooked patty of
ground meat, usually beef. Immigrants to the U.S. in the early 1900s brought with them favorite recipes,
one of which was shredded or minced cooked beef, a back-home favorite of many Germans, some of
whom were from the German city of Hamburg, and known as you guessed it, Hamburgers.
Anyway, by the 1940s, the hamburger was a fully assimilated American favorite and still is, along with its
cousin, the cheeseburger. U.S. meat producers estimate Americans eat 14 billion hamburgers a year.
Burgers start off like this: pieces of red meat, usually less-tender cuts of beef, put through a grinder.
KENT KIRSHENBAUM (New York University): The meat itself is composed of ground muscle tissue,
usually from a cow. And that will contain a large amount of protein; also contains some fats and quite a
bit of water.
ROKER: The chemistry of food, especially meat, is a research focus for Kent Kirshenbaum, a chemistry
professor at New York University funded by the National Science Foundation. As he says, meat contains
a lot of proteins, chain molecules made up of amino acids strung together like beads on a necklace.
Something like this.
KIRSHENBAUM: One of the major components of muscle, of meat, is a protein called myoglobin. That
is composed almost completely of helices or coiled regions of the protein chain.
ROKER: Helices is the plural of helix, a shape like a spring, or a spiral staircase. You may be familiar
with DNA: a double helix.
KIRSHENBAUM: These helices are bundled together within the protein structure, and deep inside that
protein there is a component of the protein that has one iron atom tucked away right in the center of it.
Myoglobin was actually the very first protein whose structure was understood or solved.
ROKER: A feat that won two British chemists, John Kendrew and Max Perutz, the Nobel prize in
© 2008-2015 NBCUniversal Media, LLC. All Rights Reserved.
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chemistry in 1962. Myoglobin is a major reason red meat is red.
KIRSHENBAUM: The red color that we see in meat is actually not coming from the blood. That red color
is coming from that myoglobin molecule in the meat tissue.
ROKER: That is, in fresh, raw meat. Meat changes color, in a series of chemical reactions, when you
apply heat: Put a burger on a grill or in a skillet, and it turns brown because of what happens to the
myoglobin as you’re about to see. Julie Yu is an NSF-funded chemist at The Exploratorium in San
Francisco.
JULIE YU (The Exploratorium): So we’re gonna cook some hamburger patties two different ways, and
we’re gonna see how the color of the patty tells us something about the chemical reactions that took place
as it cooked. I’m gonna put one patty into this boiling water. And you can see pretty instantly that the
color of the meat changes, from the bright red that it was when it was raw to kind of this dull gray. And
this other patty, I’m gonna put into this pot. So the sizzle that you hear when the raw meat hits the hot
plate is actually the water molecules on the surface of the meat, boiling off. So the temperature of this pot
is very high.
ROKER: As the burgers cook, the myoglobin proteins in the meat do what atoms and molecules generally
do when heated: move, or vibrate, faster and faster, which denatures the proteins, changing their natural
shape.
KIRSHENBAUM: Generally, proteins are very carefully composed into precise arrangements. When we
add heat to hamburger meat to cook it, the atoms in those proteins could begin to move around, and those
very careful arrangements could begin to become scrambled or unfolded.
ROKER: As the proteins change shape, or denature, particularly around the iron atoms, the color changes.
The burger boiled at one temperature turns grayish brown. The burger pan-fried at a higher temperature is
a richer, darker brown.
YU: And the texture of it is a little crusty, compared to the soft, boiled burger.
ROKER: That darker browning on the outside of the fried burger is due to what’s called the Maillard
reaction. Louis-Camille Maillard was a French chemist in the early 1900s who studied the science of
browning. In fact, the Maillard reaction is also called the browning reaction.
Maillard found that when he heated amino acids, remember the beads in the protein necklaces? Plus
sugars like those in carbohydrates, which are in almost all natural foods, including meat, the substance
turned brown, different shades, depending on the temperature, which you can see when Julie Yu cuts her
two burgers open.
YU: When we cut inside the burgers, you’ll see that inside the color is exactly the same. The inside of the
meat patty wasn’t exposed to the high temperature of the pan and so it wasn’t able to undergo the hightemperature Maillard reaction, which create these nice crusty brown bits that are very flavorful to us.
KIRSHENBAUM: The Maillard reactions result in development of rich brown colors. And they also
generate an incredible variety of different flavor molecules as well. Other places where you might see a
browning reaction are on a nice rich piecrust, or on a nice brown piece of toast.
ROKER: A toast, then, to meat and to heat and to the chemical reactions that turn this into this.
YU: Oh, it’s so perfect. It’s gonna be the best-tasting burger ever!
© 2008-2015 NBCUniversal Media, LLC. All Rights Reserved.
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© 2008-2015 NBCUniversal Media, LLC. All Rights Reserved.
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