When raw ground beef turns brown in the refrigerator, it is a normal and natural process called oxidation. Oxidation occurs when the meat comes into contact with air, causing it to react with oxygen, and this can change the color of the meat from its original red to brown. While it may not look as appealing, browning due to oxidation is not necessarily an indication that the meat is unsafe to eat.
The key factor in determining whether raw ground beef is still safe to cook and eat after it turns brown is its smell and texture. If the ground beef smells bad, has a sour or off-putting odor, or has a slimy or sticky texture, then it has likely spoiled, and it is not safe to consume. Additionally, if there are any signs of mold or other visible spoilage, discard the meat immediately.
If the ground beef looks brown but still smells normal and has a typical texture, it should be safe to cook and eat. However, it's essential to cook it thoroughly to ensure any potential bacteria or pathogens are killed. Cooking ground beef to an internal temperature of 160°F (71°C) will help ensure it is safe to eat.
As for how many days ground beef is good for after it turns brown, it is best to use your judgment based on the smell and texture. If it still looks and smells fine, and it has been properly stored in the refrigerator at or below 40°F (4°C), it should be safe to cook and eat within 1-2 days of the browning occurring.
In general, it's always better to err on the side of caution when it comes to food safety. If you have any doubts about the quality or safety of raw ground beef, it's best to discard it and avoid the risk of foodborne illness.