As a kid I grew up being told that I had to let food cool down before putting it in the fridge. I was under the notion that placing warm food directly in the refrigerator could cause the other foods in the refrigerator to warm up. I had also been told that placing warm food in the refrigerator was a waste of energy as the fridge would have to work harder to maintain a cool temperature. I was shocked when I learned that leaving leftovers to cool on the countertop posed a potential risk for my health.
Most food regulation agencies recommend that unless the food is being consumed, it should be placed in the fridge immediately after being cooked — it should not be left to cool down on the countertop at room temperature. Moreover, when cooking large portions such as stew or chili, the best practice is to separate the large batch into smaller containers with minimal airspace and place them in the fridge for cooling.
Leaving food to cool at room temperature provides the ideal environment for any bacteria present in food to rapidly multiply. This ideal range of temperatures is known as the “danger zone” and includes temperatures between 4 and 60 degrees Celsius. Once the pathogenic bacteria establishes itself in the human host, or when humans consume food with toxins produced by the bacteria, foodborne illness can arise. Foodborne illnesses tend to have mild gastrointestinal symptoms for most individuals and will typically resolve themselves within 24 hours. However, in individuals with compromised immune system function, individuals with more sensitive immune systems such as old and young people, or when healthy individuals consume large amounts of bacteria, foodborne illnesses can have much more severe consequences. One of the most important factors for proper recovery is staying properly hydrated.
After learning that food should be left to cool in the fridge, I was asking myself how I had never gotten sick from foodborne illnesses if I had failed to follow the correct process for most of my life. The answer is probably luck and good food regulation. Not all food left out to cool is dangerous to eat; it is only dangerous if the food is contaminated. If contaminated, the bacteria in the food will flourish and multiply to dangerous levels.
While food regulations in Canada tend to be very good, when it comes to foodborne illnesses it is better to err on the side of caution. However, it is unrealistic to put the pot from the stove directly in the refrigerator. That’s why most food safety institutions tend to recommend a two-hour rule. This rule dictates that based on the bacteria’s multiplying rate, most food can be consumed safely within 2 hours of being prepared. However, this time may shorten to one hour if the food is sitting at higher temperatures. Similarly, the two hours can be extended to 4 hours in grocery stores and restaurants as these environments tend to have more strict food safety rules that minimize bacterial contamination and growth.
While placing warm food in the refrigerator might make it work extra hard and use a little more energy, that is what they are made for. My own kitchen has gone from housing leftovers on the countertop to housing them in the fridge. I think I can safely say that as a result of my newfound habit I have experienced less stomach aches in the past year.
Bottom Line:
- Eat foods soon after they are cooked
- Keep hot foods hot, at 60°C or above
- Keep cold foods cold, at 4°C or below
- Don’t let foods cool to room temperature
- If serving later, refrigerate right away
- Store cooked foods appropriately
- For foods cooked in advance, store above 60°C (140°F)
- Alternatively, rapidly cool and store below 4°C (40°F)
- Store leftovers right away in the fridge or freezer.
- Eat cream-filled pastries, and creamy salads immediately
- Alternatively, store right away in the fridge
- Make sure your fridge is set at 4°C (40°F) or below
Daniela is a recent B.Sc. graduate from the program of Physiology at McGill. She is very passionate about understanding the human body and how we can all individually adapt our daily lifestyles to improve its functioning.
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