Cooling is a process of removing heat from food quickly enough to prevent microbial growth. One method is done by placing foods in shallow containers no deeper than 2 inches and leaving them uncovered until cold, 41 degrees Fahrenheit or below.
When potentially hazardous food is cooled for an extended period, the food is subject to the growth of a variety of pathogenic micro-organisms. Bacteria grow ideally between 70 and 120 degrees Fahrenheit. (The human body temperature falls in this range). The longer the time the food is allowed to be held in this range, the greater the risk of microbial growth. Excessive time for cooling potentially hazard food has consistently been identified as one of the leading contributing factors to foodborne illness.