Leaving American cheese or any perishable food out of the refrigerator overnight is not recommended. Perishable foods, including cheese, are susceptible to bacterial growth when left at room temperature for an extended period.
American cheese, like other dairy products, contains moisture and nutrients that provide an ideal environment for bacteria to multiply rapidly when the temperature is above 40°F (4°C). Bacteria can grow to unsafe levels, potentially leading to foodborne illnesses if consumed.
The general rule of thumb is to adhere to the "2-hour rule." This means that perishable foods, including cheese, should not be left at room temperature for more than two hours. If the temperature is above 90°F (32°C), the time reduces to just one hour. After that time, the risk of bacterial growth becomes significant.
To ensure food safety, it's best to refrigerate American cheese (or any other perishable food) promptly after use. If you accidentally leave it out overnight, it's advisable to discard it rather than risking foodborne illness by consuming it.
Always practice proper food handling and storage to keep yourself and others safe from potential foodborne pathogens. When in doubt about the safety of a particular food item, it's better to err on the side of caution and dispose of it if it has been left out for an extended period.