When you are entertaining a large group of people, you may find it convenient to serve them food from a buffet, with dishes set so each person serves himself. Self-service gives people a variety of choices and makes it easier on the host, who doesn't have to bring the food to each person. However, when sharing food in a buffet, you must keep cold foods cold to prevent food-borne illness. According to the United States Department of Agriculture (USDA), keep cold foods at 4.44 degrees Celsius or colder, which you can do by putting them on ice.
Arrange food on many shallow platters instead of one large platter and keep it in the refrigerator until you serve it.
Place large bowls or other containers on the buffet table.
Pour ice cubes or crushed ice into the bowls or other containers. Crushed ice conforms better to the shape of any bowl or container to bring more ice into contact with the surface of the container and keeps the food colder.
Nest platters of food in the ice-filled containers. When a platter has been depleted, replace it with a fresh platter from the refrigerator --- do not add new cold food to a platter that already had food on it.
Monitor the ice and replenish as needed.
Do not let food sit at room temperature for more than two hours. Keep track of how long it has been sitting on the buffet, and discard it after it has been out for two hours or more, as advised by the USDA.