Traditionally, potlucks offer time for socializing. The responsibility of cooking for a large group of people is shared among many people, and cooks have an opportunity to share their favorite dishes with appreciative guests. Potlucks often set up ideal conditions for development of foodborne bacteria when food isn't maintained safely, so take steps to keep your warm dish at the right temperature.
Even food prepared in the cleanest kitchen and under the safest conditions can develop bacteria, especially when the food is transported a considerable distance or is allowed to sit at room temperature. Bacteria is dangerous because you can't see, smell or taste it, but it can result in foodborne illness and a number of unpleasant symptoms, including vomiting, diarrhea, cramps, headache and fever. Foodborne bacteria is especially dangerous for people with weakened immune systems, as well as infants, the elderly and pregnant women.
Once a hot dish is prepared, it must be maintained at a temperature of at least 140 degrees Fahrenheit to prevent development of dangerous bacteria. If you have to transport a hot dish to a potluck, wrap several layers of aluminum foil around the casserole dish, then wrap the dish with a thick towel or several layers of newspapers or paper grocery bags. Place the entire package in an insulated cooler. If possible, prepare hot dishes just prior to the potluck. If you make the dish ahead of time, refrigerate it and then reheat it to a temperature of at least 165 F.
Test the temperature of the hot dish before serving. If the temperature drops below 140 F. during transportation, the food must be reheated quickly to a safe temperature of 165 F. and held at that temperature for at least 15 seconds, as bacteria develops quickly between 40 and 140 F. Don't heat the food in a slow cooker or chafing dish, which heat too slowly to kill bacteria. Use the oven, stove top or a microwave oven to heat the food quickly.
Serve hot food immediately and discard food that remains in the temperature danger zone for more than two hours. If the ambient temperature is above 90 F., such as a potluck picnic on a hot day, eat or refrigerate the food within one hour. Potluck leftovers are safe to use if the food is refrigerated within the safe time zone; otherwise, it should be discarded.