Is Your Meat Fresh? You Can't Judge the Meat by Its Color! You may have seen the news stories that some packaged supermarket meat is treated with carbon monoxide to help retain its red color. Opponents say the carbon monoxide, though not harmful, could mask spoiled goods. So how do you know which grocery meat is fresh? "You can't judge by the color," says Delia Hammock, R.D., the Good Housekeeping Institute's Nutrition Director. "Look for the sell-by date. And when you open the package, check the meat's texture and smell. If the meat is slimy or smells bad, throw it away."