Cooked food is most at risk while it cools, because it passes slowly through the temperature danger zone. Two-stage cooling is a widely used rule that sets time limits on each part of the cooling curve. In the first stage, food is brought from around 60 °C down to about 21 °C within two hours, the range where bacteria grow fastest. In the second stage, it is brought down to 5 °C or below within the next four hours.
The first stage is the harder one. A deep pot of dal or a large tray of biryani cooling on the counter or in a reach-in will not meet it. Kitchens meet the rule by dividing food into shallow pans, stirring, using ice baths or ice wands, leaving lids off while hot, and above all by using a blast chiller. Core temperatures should be checked with a clean probe thermometer and recorded.
A school meal kitchen in Pune cooking rajma in bulk for the next day might portion it into shallow GN pans, blast chill it, check that it reaches the stage limits on time, and log the readings before moving it into cold storage.