What is the risk: cooling hot food?
Food safety is about managing risk. It’s about focusing on practices that address risk factors known to contribute to foodborne illness. Some practices are more critical or risky than others. Let’s focus on proper cooling of hot food.
Improper cooling practices are a major cause of foodborne illness. In the United States between 1998 and 2008, improper cooling practices contributed to 504 outbreaks linked to restaurants and delis. Research conducted in 2010 by the Centers for Disease Control and Prevention (CDC) and several state health departments including the Minnesota Department of Health, shows the data collected indicate that many restaurants are not meeting the recommended cooling processes. A total of 420 restaurants (50 from Minnesota) participated in the study. Findings from these studies suggest that greater emphasis needs to be placed on the best practices of cooling hot food to reduce the risk of foodborne illness.
Temperature danger zone and 2-stage cooling
Microorganisms grow well in the temperature danger zone, 140° – 41°F. Within this range, temperatures between 125° – 70°F allow for the most rapid growth of microorganisms. For this reason food must pass through this range quickly. The 2-stage cooling method is approved in Minnesota.
Minnesota Food Code states cooked potentially hazardous food or TCS food (foods that need time and temperature control for safety) shall be cooled:
- from 140°F to 70°F with two hours; and
- from 70°F to 41°F or below within four hours.
The initial 2-hour cool is the most critical time period since the food is passing through the temperature range that supports the most rapid microorganism growth. If food has not reached 70°F within two hours, it must be reheated to 165°F for 15 seconds and then cooled again or thrown away.
Best practices for cooling food
Food needs help cooling down quickly; it can’t do it on its own. Factors that affect how quickly foods will cool down include:
- Size of the food item being cooled — the thickness of the food or distance to its center plays the biggest part in how fast a food cools.
- Density of the food — the denser the food, the slower it will cool. For example, chili will take longer than chicken noodle soup.
- Container in which a food is stored — stainless steel transfers heat from foods faster than plastic. Initially loosely wrap food items.
- Size of container — shallow pans with product depth less than two inches allow the heat from food to disperse faster than deep pans.
Food does not move through the temperature danger zone fast enough if the food is still hot when placed in the cooler or freezer or kept in bulk. Placing hot food in a cooler may raise the temperature of everything being held and may put it in the temperature danger zone.
Start by reducing the size or mass of food by cutting large food items into smaller pieces and dividing large containers into smaller containers. Approved and efficient ways to cool food include:
- Ice-water bath and frequently stirring the food for faster and more even cooling
- Ice paddles (plastic container filled with water and frozen) used to stir food in an ice-water bath
- Adding ice as an ingredient (if water is an ingredient)
- Blast or tumble chiller
- When placed in cooling or cold holding equipment, food containers in which food is being cooled can be loosely covered or uncovered if protected from overhead contamination, to facilitate heat transfer from the surface of the food.
The only way to accurately know that time and temperature requirements are being met is by monitoring the process. Staff training needs to include: how and when to check temps, how to calibrate thermometers and how to keep accurate time-temp logs.
Center for Disease Control and Prevention. 2012. Foodborne Outbreak Reporting System. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, Atlanta; Journal of Food Protection, Vol.75, No. 12, Pages 2171-2178; Iowa State University Extension, 2013. Food Safety Project; MN Food Code 4266.0385 3-501-14 and 3-501-15.
Keep Food Safe with Time and Temperature Control — Background information and links to Minnesota Department of Health (MDH) fact sheets and Minnesota Department of Agriculture (MDA) posters.
Cooling Potentially Hazardous Foods — Minnesota Department of Health — Fact sheet
SOPs for Flow of Food in restaurants — Scroll down the list for the information on Cooling Food and Cooling Temperature Log.