For generations, a common kitchen myth has persisted: putting hot food in the refrigerator is a recipe for disaster. Concerns range from warming up other foods to making your fridge work overtime. But what does science actually say? Is it really harmful to place that steaming pot of soup directly into the cool confines of your refrigerator?
The good news is that, contrary to popular belief, food safety experts actually recommend refrigerating hot food promptly. Leading authorities like the United States Department of Agriculture (USDA) advocate for refrigerating hot food as soon as possible to minimize the risk of bacterial growth. The key is to do it correctly.
The fear likely stems from outdated practices related to iceboxes, the refrigerator’s historical predecessor. As explained by Helen Peavitt, a social historian and author of “Refrigerator: The Story of Cool in the Kitchen,” iceboxes relied on blocks of ice to maintain coolness. Introducing hot food would indeed melt the ice faster, reducing the appliance’s efficiency and requiring more frequent ice replenishment.
Modern refrigerators, equipped with chemical refrigerants and efficient cooling systems, are far more robust. However, to ensure both food safety and energy efficiency, there are best practices to follow when refrigerating hot meals.
Best Practices for Refrigerating Hot Food
The primary concern with leaving food out at room temperature for extended periods is the “danger zone” – temperatures between 40°F and 140°F (4°C and 60°C) where bacteria multiply rapidly. To combat this, rapid cooling is essential.
Experts recommend dividing large portions of hot food into smaller, shallower containers. This simple step significantly speeds up the cooling process. For dishes like lasagna, large roasts, or casseroles, portioning them before refrigeration is crucial. Shallow containers, ideally no more than two inches deep, are perfect for storing soups and stews. Initially, loosely cover these containers to allow steam to escape, which also aids in faster cooling. Once the food has cooled down somewhat, you can seal the containers tightly.
According to the Food and Drug Administration (FDA), it is safe to refrigerate hot food directly, even while it’s still piping hot, provided it’s done within a maximum of two hours after cooking (or just one hour if the ambient temperature is above 90°F/32°C). Ensuring adequate air circulation around the food in the refrigerator is also important for efficient cooling.
However, placing very hot food directly in the fridge does make your appliance work harder, potentially increasing your energy consumption. To mitigate this, consider accelerating the initial cooling process before refrigeration. Stirring the food occasionally while it cools and placing the container in an ice bath – a sink or large bowl filled with ice water – are effective methods to lower the temperature quickly before it goes into the refrigerator.
To maintain optimal food safety, always ensure your refrigerator is functioning correctly. Using appliance thermometers to monitor the temperature is a wise move. The refrigerator temperature should be at or below 40°F (4°C), and the freezer should register at 0°F (-18°C).
Freezing Hot Food: A Slightly Different Approach
When it comes to freezing hot food, a slightly different approach is recommended for optimal quality. While immediate freezing is safe from a food safety perspective, slower freezing can lead to larger ice crystals, which can negatively impact the texture of the food upon thawing. The USDA advises that faster freezing results in smaller ice crystals, preserving food texture better. This is especially true for meats, seafood, fruits, vegetables, and creamy sauces, which can suffer textural changes if frozen too slowly.
Therefore, before freezing, it’s beneficial to cool hot food down more thoroughly than you might for refrigeration. An ice bath is highly recommended for foods intended for the freezer. You can also give the food a head start in the refrigerator before transferring it to the freezer.
When freezing liquids, remember that they expand as they freeze. Always leave adequate headspace in containers to prevent them from cracking or exploding. Kantha Shelke, a food safety regulations expert at Johns Hopkins University, suggests leaving an inch of space for pint-sized containers and 1.5 inches for quart-sized or larger containers. Even for solids, leaving about half an inch of headspace is advisable to allow for expansion and ensure a tight seal.
Choosing the Right Containers
Selecting appropriate containers for both refrigerator and freezer storage is important for food safety and quality. Glass containers, particularly tempered glass, are an excellent choice. They are durable, don’t absorb odors or stains, and are safe for reheating in ovens and microwaves. However, they can be heavier and more prone to breakage.
Silicone bags are a lighter and less fragile alternative, but they can be more challenging to clean and may retain odors. Aluminum foil and freezer paper are useful for wrapping irregularly shaped items.
Avoid placing hot food directly into plastic containers, especially those not designed for food storage. Heat can cause certain plastics to leach chemicals like BPA, phthalates, and potentially PFAS into your food, particularly if the plastic is older or repeatedly exposed to acidic or oily foods. Single-use plastics like takeout containers and yogurt tubs are not intended for reuse or heat exposure and should not be used for storing hot food. Always opt for containers specifically labeled as freezer-safe for freezer storage.
Considering Outdoor Cooling (With Caution)
In situations where you need to cool food quickly, particularly during cooler seasons, outdoor cooling might seem like an option. While it can be helpful as a temporary measure, it’s not a reliable substitute for refrigeration or freezing. Betty Yaohua Feng, a food science professor at Purdue University, advises caution due to unpredictable outdoor temperatures.
A cooler with ice packs provides a more controlled and safer environment for temporary cooling, especially for drinks and less perishable items. If you do opt for outdoor cooling, ensure food containers are tightly sealed to prevent contamination from dust and animals. Avoid direct sunlight and constantly monitor the temperature to ensure it remains below 40°F (4°C).
Holiday Fridge Management
During holidays or large gatherings, managing refrigerator space efficiently becomes even more critical. Before a big feast, take the time to declutter your refrigerator. Many commonly refrigerated items, such as unopened jars of pickles, ketchup, peanut butter, and certain fruits, do not actually require refrigeration. Freeing up space by removing these items can make room for leftovers and improve air circulation, enhancing the overall efficiency of your refrigerator and ensuring safe food storage.
By understanding the science behind food cooling and following these best practices, you can confidently refrigerate hot food, ensuring both food safety and the longevity of your delicious meals.
