What does brown ring in raw meat mean?

Answer 1

"Color of Beef

Beef muscle meat not exposed to oxygen (in vacuum packaging, for example) is a burgundy or purplish color. After exposure to the air for 15 minutes or so, the myoglobin receives oxygen and the meat turns bright, cherry red.

After beef has been refrigerated about 5 days, it may turn brown due to chemical changes in the myoglobin. Beef that has turned brown during extended storage may be spoiled, have an off-odor, and be tacky to the touch."

from http://www.fsis.usda.gov/Factsheets/Beef_from_Farm_to_Table/index.asp