Which of the following is a proper method for keeping food cold during a buffet service?

Using ice to keep food cold is a proper method during buffet service because it effectively maintains a safe temperature for perishable food items. The ideal temperature range for keeping cold foods safe is at or below 41°F (5°C). Ice serves as a reliable coolant that prevents the growth of harmful bacteria, which can proliferate when food is not kept at the appropriate temperature.

By placing food items in or on ice, it ensures that they stay within the safe temperature zone for the duration of the buffet. This method is particularly effective for items that can spoil quickly, such as salads, seafood, and dairy products. Additionally, the use of ice can be visually appealing and inviting for guests, while also offering practical protection against foodborne illnesses.

In contrast, the other methods listed would either fail to maintain safe temperatures or create conditions conducive to bacterial growth. Covering food with foil can help retain warmth but does not provide cooling. Placing food in hot water would pose the opposite effect, keeping food at unsafe temperatures. Allowing food to cool at room temperature is unsafe and can lead to the rapid growth of bacteria.