Gray Hamburger

Why is prepackaged hamburger sometimes red on the outside, but a grayish brown on the inside? It makes me wonder if fresh meat has been added to the outside to make something that didn't sell look better to the buyer.

The color difference you see occurs naturally. Red meat contains a pigment called oxymyoglobin.  This natural pigment combines with oxygen and changes the color when meat is exposed to air.  This red color is referred to as "bloom." The inside area of the meat is darker because of lack of oxygen, yet it is just as wholesome as the outer, red area.

Fresh meat in vacuum sealed packages is also dark in color until the surface is exposed to air.  This meat may also have an unusual odor which will disappear after the meat is removed from the package.

Once purchased, fresh ground meat should be used within one to two days for highest quality and safety. If it needs to be stored longer than that, it should be frozen then defrosted in the refrigerator.

Be sure to cook ground beef to 160 degrees Fahrenheit or until the juices run clear and no pink color remains.

Information developed by Carolyn Rude, Retired WSU Extension Faculty - Family Living
March 1997

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