Why Does Meat Turn Brown When Cooked?

Oct 28, 2011 8:01 am

Color commentary on the state of your steak

why does meat turn brown?
Photo: VirtualErn on Flickr
What causes red meat to turn brown? Yup, you guessed it. Science.
 

One of the best gauges of a good chef is the ability to prepare meat to order. When dining out, getting exactly what you want is something that should never be sacrificed. The same principle of impeccable cooking is just as important in the home kitchen as it is in the restaurant world. So how do professional chefs know when meat is ready to plate and serve? One of the easiest ways: by sight.

What’s the deal with red and white meat?
Though the most obvious difference between raw and cooked meat is its appearance, not all meats are created equal, so you’ll need a little bit of background on both red and white meat in order to understand what happens when either type is cooked.

While raw white meat appears translucent and glassy, red meat — as the name implies — appears bright red, often crimson in color. The difference here is the presence (or lack) of an oxygen transport molecule known as myoglobin. Without it, and without a steady supply of oxygen, the muscle fibers of red meat would be unable to sustain prolonged function, resulting in fatigue. The characteristic red color is a direct result of myoglobin, as it contains iron. Much the same way the surface of Mars appears red, so does raw red meat.

Why does meat change color when it’s cooked?
When heat from your stove, oven or grill is applied to white meat, the proteins within the muscle begin to break down in a process called denaturation. Further heating causes the denatured proteins to recombine, turning opaque and white in color, akin to when you fry an egg and the whites become white. For chicken, this occurs at 180 degrees.

Cooking with red meat is an entirely different story as different folks prefer different levels of "doneness." In any case, when heat is applied to red meat, myoglobin begins to transform. At 140 degrees Fahrenheit — the temperature at which red meat it considered "rare" — myoglobin remains relatively intact with little to no change in color. As the internal temperature of the meat rises above 140 degrees, however, myoglobin loses its stability and forms a new molecule called hemichrome. Hemichrome is the compound that gives medium-cooked red meat its slightly browned color.

We’re not done yet. Internal temperatures continue to climb until the meat has reached a blistering 170 degrees Fahrenheit, the point at which it’s considered "well-done." By this time, the myoglobin has been completely altered and has lost all of its red color. While some would call this charred and ruined, others find the crispy carbon-rich exterior divine.

How do you like your meat?

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