Answer:
The total amount of time that the FDA recommends the entire cooling process of food take, divided into two separate stages of cooling, is 6 hours.
Of these six hours, the process is further divided into two critical stages, one of which does not have options as to how to divide the time, and the other that is more flexible.
Thus, the first 2 hours are known as stage 1 of the cooling process of food, and the second stage takes about 4 hours. Stage 1 is absolutely unmovable and its objective is to bring the heat in food from 135°F to 70°F in 2 hours, or less. The FDA explains that this stage is known for being the danger zone, as bacteria tend to thrive best at this range of temperatures. Stage 2 has the more number of hours, with 4 hours left, to finish the cooling process. In this stage, heat must be brought from 70°F to 41°F.
The purpose of this is to bring down the temperature of food safely, but as fast as possible, to prevent dangerous pathogenic bacteria from growing in hot food and putting people in danger.