Frozen meat should not be left out for more than two hours, advises the U.S. Department of Agriculture. As soon as any part of the meat reaches 40 degrees Fahrenheit, harmful bacteria start to grow and multiply, presenting the risk of foodborne illness and cross-contamination. This applies to both pre-cooked and raw frozen meats. Meat can be cooked from frozen, although not in the slow cooker -- just increase the cooking time by about 50 percent. Alternatively, defrost the meat before cooking it.

Thawing meat in the refrigerator is the best way to defrost, but it also takes the most time. The main advantages to this method are that the gentle defrosting process will result in less damage to the texture of the meat, and that you don't have to cook the meat immediately once thawed -- you can even refreeze it. Keep in mind that large cuts of meat may take days to thaw -- factor in 24 hours for every 5 pounds of meat.

A faster way to safely defrost meat, but one that requires more attention, is the cold water method. Keep your meat in its original packaging or seal it in a heavy duty zip-top bag and submerge it in a vessel of cold water. Change the water every 30 minutes to keep it cold. A 1-pound package of meat may take less than an hour to defrost, while a large piece of meat, such as a whole turkey, will take about 30 minutes per pound. Once defrosted, cook the meat straight away -- don't store it in the refrigerator or refreeze it.

The fastest way to defrost meat is to use the microwave, but this may result in a decline in quality -- particularly, the texture of areas that may cook while the rest of the meat continues to defrost. To minimize the damage, use the "Defrost" mode or set your microwave to 50 percent power. If the meat is in pieces, such as chicken wings, separate the pieces as they defrost for more even thawing. You must cook the meat immediately once defrosted.