What is NOT one of the four acceptable TCS food thawing methods?

The correct answer is that thawing at room temperature is not an acceptable method for thawing TCS (Time/Temperature Control for Safety) foods. Thawing foods at room temperature allows them to remain in the temperature danger zone (between 41°F and 135°F), where bacteria can multiply rapidly, increasing the risk of foodborne illness.

In contrast, the other methods mentioned for thawing TCS foods are considered safe because they minimize the potential for bacterial growth. Thawing in cold running water ensures that the food remains at a safe temperature throughout the thawing process. Thawing in the refrigerator keeps the food at a consistent, safe temperature. Using a microwave oven can be safe provided that the food is cooked immediately after thawing, as this method can also heat food unevenly, which may leave some parts within the danger zone if not followed by cooking. Therefore, thawing at room temperature is the only option listed that poses a significant risk of bacterial growth, making it an unacceptable method.