WASHINGTON — A new educational video about the color of ground beef found in today's meat cases has been unveiled by the American Meat Institute. Featuring Betsy Booren, Ph.D., director of scientific affairs of the American Meat Institute Foundation, the video is the sixth installment of A.M.I.'s new "Ask the Meat Scientist" series.

A wide range of choices in today's meat case are resulting in many different questions from consumers. Ground beef sometimes may appear red on the outside, but brown on the inside due to packaging methods. Ms. Booren explains in the video that oxygen is the simple explanation for this.

"Beef comes from the muscle of an animal,” she said. “In its natural state — when it is not exposed to any oxygen — it appears purple. But when it is exposed to at least a 20% or higher oxygen level of air, the protein responsible for meat color, called `myoglobin,' is forced to bind with the oxygen present and causes the meat color to turn red. Also, when the meat is exposed to no or less than 1% of oxygen gas, the meat color will change to a brownish shade."

Many retail outlets package their ground beef on a styrofoam tray covered with plastic wrap, or overwrap packaging. Since some oxygen is able to penetrate the plastic wrap, it can make the outside of the meat appear bright red.

Some consumers ask if beef's red color comes from food coloring, but this certainly isn't the case, Ms. Booren notes in the video. "The U.S. Department of Agriculture inspects all ground beef and food coloring is not allowed to be added,” she added. “Color is simply a natural interaction between beef and the oxygen in our everyday environment.”

Go to A.M.I.'s YouTube channel, The Meat News Network, at http://www.YouTube.com/MeatNewsNetwork, to view the video.