Reheating is the thermal process to heat foods that have been previously cooked and cooled in a food service establishment. Proper reheating can eliminate a major portion of pathogens. Proper reheating is heating a food to 165 degrees Fahrenheit within 2 hours.
The more a food is processed, the greater the risks. When food is held, cooled and reheated, there is an increased risk from contamination caused by personnel, equipment, procedures and other factors. When food is cooked and cooled the product goes through the danger zone (optimal temperature range for microorganisms to grow) several times which also increase the risks.