It depends on the type of food it is
The legal temperature for food served from a heated trolley is over 63 Degree Celsius. The food should be at this temperature to prevent any bacteria contamination of food.
You measure food temperature when the food looks cooked. if it does not reach the temperature that it should then you will need to cook it for longer even though it is cooked on the outside. you can get sick from eating uner cooked food.
Food should be reheated to an internal temperature of at least 165°F (74°C) to ensure that it is safe to eat. This helps to kill any bacteria that may have grown on the food while it was stored. Make sure to use a food thermometer to check the temperature before consuming.
Cold food should be served at or below 41 hot food should be at or above 135
Food temperature is generally checked by inserting the probe into the thickest part of the food, using a sanitized, calibrated, instant-read thermometer.
It depends on the food. But food and safety laws state dairy should be kept at 40F or below.
Blinks
Leftover food should be reduced to room temperature before storing. It can be refrigerated or frozen.
Bacteria in food reaching a temperature of no more than 63c is very dangerous. Bacteria thrive at this temperature. Food is in what can be referred to as a 'high risk or danger zones'. Food should not be consumed and should be destroyed.
It should be kept at room temperature. You can leave it in a closet and that will be fine
Hot food should be held at 140 °F or warmer.