A whole beef tenderloin packaged in a vacuum bag will normally appear purplish-red in color. This is due to the absence of oxygen in the vacuum package. Once meat is removed from a vacuum package and exposed to air, the surface of the meat will turn bright red. The interior of the muscle will remain purple because oxygen cannot penetrate to the center of the meat. Both the purple and red colors are natural for fresh meats.
Ground beef packaged in a tray overwrapped with film generally appears bright red in color.
If you broke the ground beef apart to expose the inside, the color would appear dark brown to purplish. As this internal portion is exposed to air, it will also turn a bright red color. Over time, however, prolonged exposure to air will cause the color of the exposed surfaces to turn brown. This color change is normal. Fresh meat that smells fresh and appears brown in color is safe to cook and eat, but should be quickly frozen if you do not intend to prepare and consume it within a day.