Free Guide
Cooling and Storing Food Safely
Ph.D., Hospitality and Tourism Management, Purdue University, 2014
Doctoral research and specialization in food safety · ServSafe Certified
Why cooling and storing matter
Most home cooks are careful while the food is cooking and relax the moment it comes off the heat. That is backwards. Cooking kills most bacteria, but the food is then left to cool slowly on the stove, packed hot into one deep container, or kept a few days too long, and the survivors and their toxins get the time they need.
In my food-safety guide I said contamination can happen at every step: preparing, cooking, serving, cooling and storing. This guide covers the last two, and thawing, which is where the next meal starts.
The danger zone and the two-hour rule
Bacteria grow fastest between 41°F and 135°F (5°C to 57°C), the range the FDA Food Code uses; USDA’s advice for home cooks rounds it to 40°F to 140°F. That range is the danger zone, and the goal is to get food through it as fast as you can, in either direction.
- Keep hot food at 135°F (57°C) or hotter, and cold food at 40°F (4°C) or colder.
- Perishable food should not sit at room temperature for more than 2 hours in total, counting from when it came off the heat or out of the refrigerator.
- If the room or the picnic table is above 90°F (32°C), that limit drops to 1 hour.
- Past that, throw it out. Reheating does not make it safe again, because some bacteria leave behind toxins that heat does not destroy.
Cooling hot food quickly
Refrigerate leftovers within 2 hours of cooking. Hot food can go straight into the refrigerator; you do not need to let it cool on the counter first, and the counter is where the time gets wasted. What matters is how fast the middle of the food gets cold.
- Divide big batches. A full stockpot of chili or soup holds its heat for hours. Split it into shallow containers so no part is far from the cold air.
- Cut large items down. Slice roasts and hams, and carve a turkey: slice the breast meat; the legs and wings can stay whole.
- Use an ice bath for soups, stocks and sauces. Set the pot or container in a sink of ice water and stir. It is the fastest way to get liquid down through the danger zone.
- Leave room for air. Don’t stack hot containers tightly in the refrigerator; cold air has to move around them.
- Cover and seal once the food is cold, to keep it from picking up other smells and drying out.
Restaurants work to a stricter, two-stage standard from the FDA Food Code: from 135°F to 70°F within 2 hours, then from 70°F to 41°F within the next 4 hours, six hours in all. That is how a professional kitchen proves a big batch cooled safely, and a thermometer in the center of the container is how you would check it at home.
Storing leftovers
How long cooked leftovers keep in the refrigerator depends on whose rule you follow. USDA’s advice for home kitchens is 3 to 4 days at 40°F (4°C) or colder. The FDA Food Code, which restaurants work to, allows up to 7 days at 41°F (5°C) or colder, counting the day the food was cooked as day 1. If you will not eat them in time, freeze them; don’t wait until the last day to decide.
| Where | Temperature | Cooked leftovers keep |
|---|---|---|
| Refrigerator, USDA home advice | 40°F (4°C) or colder | 3 to 4 days |
| Refrigerator, FDA Food Code | 41°F (5°C) or colder | Up to 7 days, the day it was cooked counted as day 1 |
| Freezer | 0°F (−18°C) | 3 to 4 months for best quality |
A few high-sugar foods are exceptions to those limits, because so much sugar leaves bacteria too little free water to grow. A well-made fruitcake keeps for weeks in the refrigerator. Lemon curd made with full sugar and cooked to 170°F keeps up to 4 weeks refrigerated, or up to a year frozen, according to the National Center for Home Food Preservation. For those, follow the storage time in the recipe rather than the leftover rule. A reduced-sugar version is not covered by that exception.
Food held at 0°F stays safe indefinitely. The 3-to-4-month figure is about quality: frozen food slowly dries out and loses flavor. A refrigerator thermometer costs a few dollars and tells you whether yours is really at 40°F; many run warmer than their dial suggests.
Label containers with what is in them and the date you cooked it. Your nose is not a safety test: the bacteria that make people sick usually do not change how food smells or looks.
Reheating leftovers
Reheat leftovers to 165°F (74°C), checked with a thermometer in the thickest part.
- Bring sauces, soups and gravies to a rolling boil.
- Cover food while it reheats, so it heats through evenly and stays moist.
- In the microwave, cover and vent the dish, stir or rotate partway through, and add a little liquid if it looks dry. Let it stand a minute or two, then check the temperature in several spots: microwaves leave cold pockets.
- Frozen leftovers can be reheated without thawing first, in a saucepan or the microwave for soups and stews, or in the oven or microwave for casseroles. It simply takes longer.
Thawing safely
Never thaw meat, poultry or seafood on the counter or in hot water. The outside sits in the danger zone for hours while the middle is still frozen. There are three safe ways, and one shortcut: cook it from frozen.
| Method | How long | After thawing | Can you refreeze it? |
|---|---|---|---|
| Refrigerator | About 24 hours for every 5 lb; a pound of ground meat overnight. | Ground meat, poultry and seafood: cook within 1 to 2 days. Roasts, steaks and chops: within 3 to 5 days. | Yes, without cooking, though it may lose some quality |
| Cold water | At home: in a leak-proof bag, fully submerged; change the water every 30 minutes. Use it only for small packages that thaw within about 1 hour, around a pound. Anything larger, including a whole turkey, thaw in the refrigerator. In a restaurant: restaurants generally have availability for increased water usage, so they would generally place the frozen item in a bowl in a sink and allow a slow run of cold water to help defrost quickly, without having to change the water. This method is for no more than 4 hours total. | Cook immediately | Only after cooking |
| Microwave | Follow the microwave’s defrost setting; parts of the food start to cook. | Cook immediately | Only after cooking |
| No thawing | Cook straight from frozen; allow about 50% longer. | — | — |
Plan ahead and the refrigerator is the method to choose: it is the only one where the food never warms into the danger zone. With leftovers, if you only need part of a container that thawed in the refrigerator, take that portion out and refreeze the rest without reheating it.