Myth-Busting: A Popular Food Safety Misconception
During one of my community rotations in my dietetic internship, I heard someone say that if you put hot food directly into the fridge without letting it cool down first, it will spoil.
After asking around, it seems like this is a common ‘rule’ people have been told at some time in their lives, and have continued to abide by.
This is inaccurate and unsafe.
Although some may have been told this by their parents or grandparents at some point in their lives, this is actually not true. In fact, it’s pretty much opposite of the truth. The goal is to get hot food into the fridge as soon as you can! Let’s break this down a little bit more:
There are many contributing factors that can come together to cause our food to be unsafe. This ranges from external chemical or physical contaminants that can wind up in our food, to incorrect food handling behaviors that can lead to foodborne illness. This myth in particular focuses on just a few aspects of the latter, out of the many, many circumstances that can lead to poor food safety. This post does not serve as an all-inclusive guide on all aspects of proper food safety.
What conditions do bacteria thrive?
Bacteria can be responsible for making us sick, and can lead to food poisoning. Warmth and moisture are two of the conditions that encourage bacterial growth:
Really hot and really cold temperatures stop growth or kill bacteria, keeping our food safe! The in between temperatures are known as the temperature danger zone, where the temperature is ideal for bacteria to thrive in. The ‘Danger Zone’ is between 40 F and 140 F. Room temperature happens to be in this temperature danger zone, so leaving food out at room temperature or waiting for something to cool on the counter, actually encourages bacteria to grow.
Any prepared food has some level of moisture, or water content. This is why shelf stable foods are things like dried beans and pastas which have no water content until they are cooked, and do not spoil at room temperature. Bacteria need energy to grow and multiply. Water is needed to dissolve the food they use for energy and get it into their cells.
How long is safe?
If we are saving hot foods, like leftovers, to enjoy another time, we want to get it below the danger zone in the fridge or freezer within 2 hours. This is a timeframe developed using science determined by how fast bacteria grows. The amount bacteria grows within two hours, is not typically considered worrisome in terms of food safety. After two hours, the amount of bacterial growth could pose a food safety risk. The longer food stays in the ‘Danger Zone,’ the higher the risk for foodborne illness.
If you wait until something fully cools, then put it in the fridge, it will likely take much longer than the safe two hour window, and pose a health risk. This is because the hot food contains water (making energy available to bacteria), and a desired warm temperature for bacteria to grow and multiply. Leaving food at room temperature for more than two hours increases the risk of foodborne illness. The correct food safety practice is to get food in the fridge or freezer as soon as feasible to avoid this! When you do refrigerate or freeze leftovers, the size of the container does make a difference. Hot food should be stored in multiple shallow containers instead of one large pot or deep Tupperware container. When a large volume of hot food is stored, it will take longer for the entire volume to come down to temperature, and can create pockets of food that remain in the danger zone more than two hours. Another alternative is to use a frozen wand to stir through larger volumes to aid in cooling down to safe temperatures. When these guidelines are followed, there is no scientific reasoning that hot food would spoil in the fridge-- it’s just the opposite! So from now on make sure you’re getting food to the proper temperature within 2 hours, and share this with anyone you know that could benefit from this!
For more information of proper food safety click here
**Disclaimer: this is not all-inclusive information on the causes, and contributors to food safety and foodborne illness.
References & Resources
ServSafe coursebook (7th ed.). (2017). Chicago, IL: National Restaurant Association Educational Foundation.
*This is the training book used when I was ServSafe certified (Manager)