Final answer:
Hot food must be kept at a minimum temperature of 140 degrees Fahrenheit (60 degrees Celsius) on a steam table to ensure it's safe for consumption and to prevent bacterial growth.
Step-by-step explanation:
The coldest temperature hot food must be kept at on a steam table to maintain safety is 60 degrees Celsius (140 degrees Fahrenheit). This temperature is the minimum required to prevent the rapid multiplication of bacteria which can lead to foodborne illnesses. If the food's temperature drops below this threshold, there's a higher risk that harmful bacteria will grow, especially if the food remains in the danger zone for over two hours. It's important to regularly use a thermometer to check the temperature of hot foods on a steam table to ensure they are within the safe range, thus preventing potential health risks.