Like eggs and raw chicken, ground beef -- and ground meat in general -- is a food that knowledgeable cooks treat with extra caution. It can easily become contaminated with bacteria, either at the processing facility or after you bring it home, and has a limited storage life in your refrigerator. Cooks are often uneasy about refreezing ground beef after it's been thawed, fearing its potential for foodborne illness. It is possible to do this safely, as long as you understand and follow food safety guidelines.
Ground Is a Challenge
Paying close attention to food safety is crucial when you're handling any raw meat, but it's especially important with ground beef or other ground meats. Bacteria collect on the exposed surfaces of meats, and ground meat is almost all surface area. Even more important, any bacteria that might have been present on the original cut are circulated throughout the meat once it's ground. This can give potentially harmful bacteria a substantial head start, but it doesn't mean you can't thaw and refreeze the beef.
The U.S. Department of Agriculture recognizes three safe methods of thawing for frozen foods. If you plan to cook the ground beef immediately, you can thaw it in your microwave or in watertight packaging under cold running water. However, if you want the option of refreezing your beef the only safe method is to thaw it in your refrigerator. A refrigerator's whole purpose is to keep your ingredients at a food safe temperature of 40 degrees Fahrenheit or below, which slows bacterial growth. If you thaw your beef overnight in the fridge it never reaches a dangerous temperature, and can be refrozen at need.
If your meal plans change and you need to refreeze the beef -- or if you've gotten a great price on previously-frozen beef at the supermarket -- its' important to freeze it as quickly as possible. The refrigerator slows bacterial growth but doesn't stop it, and the longer your beef is out of the freezer the higher its population of bacteria will be. Label the beef when you refreeze it, indicating how long it was thawed. The safe lifespan of ground beef is three days or less in your refrigerator, and every day thawed counts against that total. If you bought the beef previously frozen at your supermarket, count from the packaging date.
Then There's Quality
Aside from food safety, the other factor to think about is quality. When you freeze your ground beef, the juices that fill the meat's cells will react like any other liquid. They'll freeze and expand, rupturing cell walls in the process. When you thaw the beef much of that liquid will run off, leaving the meat drier than it began. Thawing it a second time accentuates the problem, and can cause a noticeable deterioration in the quality of the beef. It's best to use twice-thawed beef in dishes such as meatloaf, where other ingredients can make up for the lost moisture, or in meat-based soups and sauces.