There are actually four safe and accepted ways to thaw turkey breast, although each has its own set of benefits and drawbacks. The method considered the safest by far is to defrost the breast in a refrigerator, allowing the ice to melt slowly and preventing bacteria from attacking the surface of the meat. A faster method is to submerge the breast in cold water, causing the ice to melt faster than in a refrigerator, although the water requires considerable attention. It is possible to thaw turkey breast in a microwave oven, but the texture of the meat could be affected and the breast would need to be cooked immediately. A frozen turkey breast also can be placed directly in an oven and cooked, although it will take a long time to reach the proper internal temperature.
It is dangerous to thaw turkey breast at room temperature, where it would seem to defrost the quickest, because harmful bacteria will start to find the meat once the temperature on the surface rises just a little above freezing. The outside of the breast will quickly reach room temperature, meaning it will be vulnerable for quite a while as the interior thaws. The longer the outer layers of the breast are sitting out to increase in temperature, the greater the risk of harmful bacteria taking hold. Each of the accepted ways to thaw turkey breast has found a solution to this problem.
The safest way to thaw turkey breast is simply to place it in the refrigerator. This prevents bacteria from developing, because the meat is kept just cold enough that bacteria cannot grow. The disadvantage of this method is that, for a very large breast, it can take days to defrost. Turkey breast that is in the refrigerator should be placed on a dish or in a pan to prevent any juices from contaminating other items or surfaces in the refrigerator.
If time is an issue, then using a bath of cold water can thaw turkey breast quicker than in the refrigerator. This involves wrapping the breast tightly in a bag and then completely submerging it in cold water, using a weight if necessary to hold it down. This method can still take hours, however. One thing that makes this method cumbersome is that the water in which the breast is thawing has to be changed every 30 minutes to keep it clean and cold.
Many microwaves have defrosting features or instructions, and using a microwave to thaw turkey breast can work very well. The bacteria will not develop inside of microwave while it is operating, keeping the meat safe. The drawback is that, depending on the microwave and size of the cut, the outer layer of the breast might start to cook and become pale white and rubbery; it eventually will be very tough once cooked in an oven. Any turkey breast thawed in this way needs to be cooked immediately once thawed.
Some cooks put a frozen turkey breast directly into an oven and start cooking it. This technique will actually thaw turkey breast and cook it, but it will take an exceptionally long time. The temperature also will need to be adjusted to ensure that the inside cooks without completely drying out the surface. It can be difficult, if not impossible, to do any type of preparation on frozen turkey breast, because spices will not stick to the skin or penetrate the meat.