Thawing food may seem simple, but if done incorrectly, it can make you just as sick as undercooking food.
How is this possible? Let’s start by talking about temperature and bacteria.
The temperature danger zone for food
Bacteria need certain temperatures to grow. Temperatures below 41°F slow down bacterial growth and keep the bacteria from multiplying on your food. Temperatures above 135°F are too hot for most bacteria to survive.
The temperature range between these two numbers (41°F and 135°F) is the temperature danger zone. It’s called the danger zone because bacteria can multiply rapidly between these temperatures. One of the reasons we refrigerate and freeze perishable food items like meat is to keep the bacteria that naturally occurs on it from multiplying to dangerous levels.
Why you should never thaw food on the counter
It’s important to know that the freezing process doesn’t actually kill any of the bacteria in food. In temperatures below 0°F, pathogens like bacteria, yeast, and mold can’t multiply to make food go bad. However, when any part of the food warms up to temperatures above 41°F, the bacteria will be warm enough to multiply again.
This is why thawing foods on the kitchen counter is so dangerous. When you thaw food this way, its surface will thaw faster than the middle. Once the surface has thawed, and continues to sit in temperatures above 41°F, bacteria will start growing. While you waited for the rest of the food to thaw out, the bacteria could have multiplied on its surface so many times that even cooking won’t make it safe to eat!
To keep bacteria from growing out of hand, it’s important to thaw frozen foods in ways that keep it out of the temperature danger zone as much as possible. Here are four alternative methods for thawing food that will keep your food safe, in order from fastest to slowest.
Method #1: thawing by cooking
This first method is one of the fastest ways to thaw food. It’s exactly what it sounds like, thawing your food by cooking it. This method typically works best when you’re working with small pieces of food, like ground or chopped meat. The smaller the cooking area, the better.
Essentially, the purpose behind this method is to move food through the temperature danger zone quickly enough that the bacteria doesn’t have time to multiply to dangerous levels. That’s why it works so well with small pieces of food or ground meat — the food is able to separate into smaller pieces as it cooks, allowing you to cook it faster.
Depending on your cooking method, you can also use this method with whole meats. For example, you could use a slow cooker or a pressure cooker to cook a frozen chicken. It might take a while, but it could be done. Be careful with thawing whole meats during cooking, however. The interior heats up last, so you could burn the outside of the meat while the inside is still thawing.
Method #2: thawing in the microwave
Using the microwave is another fast way to thaw food. On average, defrosting in the microwave takes about 7-8 minutes per pound of food. Just like the cooking method, microwaves heat up food quickly, which gives bacteria less time to multiply.
One potential downside to this method is that microwaved food sometimes heats unevenly. Even on the defrost setting, parts of your food can be cooking while other parts are still frozen. You can combat this by mixing the food periodically during defrosting.
This is one reason why microwaving whole food items is not recommended. If it heats unevenly, the outside of the food could be cooking while the inside is growing bacteria.
Microwaving is ideal for small amounts of food, or food that will be added into a larger dish later. This lowers the likelihood of getting half-thawed food. For instance, if you were making shrimp gumbo, you could thaw shrimp in the microwave and then add it to the rest of the soup. This way, the shrimp can continue to cook in the stew and it’s not a problem if some portions of shrimp didn’t fully thaw.
Method #3: thawing in cold water
This method typically takes 20-30 minutes per pound of food and requires some planning and preparation. Cold water thawing is meant to keep the surface of your food cool enough that bacterial growth stays slow, allowing the food to slowly, safely thaw all the way through.
Unlike the first two methods, you will not be cooking the food as you thaw it, so it’s important that you keep the temperature of the water consistently at or below 70°F. You should refresh the cold water every thirty minutes or so.
One way to keep the water cold without having to continuously watch over it is to fill a bowl with cold water and leave the tap running over the food as it thaws. This does require a lot of water, but it will keep the surface temperature of your food from growing bacteria too rapidly.
If you can, keep your food in its original container or in a plastic, resealable bag to protect your kitchen sink and counter from germs.
Method #4: thawing in the refrigerator
This is by far the safest method for thawing, especially when thawing whole food items. It also takes the longest amount of time. Depending on the type of food you are thawing, five pounds of food can take 24 hours to thaw.
While this method definitely takes some planning ahead, there are many upsides to thawing your food this way:
- The refrigerator keeps the food safe from bacterial growth the entire time it thaws.
- You won’t need to keep watch over the food.
- If you decide to change the meal you had planned, you can put the food directly back into the freezer without needing to cook it first. This point is explained in more detail below.
Can you refreeze food after it’s been thawed?
As you’ve already read, germs like yeast and fungus can’t grow at 0°F or below. This means that food kept at or below zero technically stays safe to eat indefinitely, but the quality of your food decreases the longer it remains frozen.
When water freezes, it expands. When the water molecules in food freeze, they also expand, rupturing the cell walls they are housed in. Each time that happens, flavor gets lost.
On top of that, when your food thaws in the temperature danger zone (41°F to 135°F), bacteria can multiply on your food to the point of being dangerous, even if you refreeze the food. This is the biggest advantage to thawing food in the refrigerator — the food can thaw without ever entering the temperature danger zone.
You can still refreeze food if you use one of the other three thawing methods, but you should cook the food to proper temperatures before sticking them back into your freezer. This extra step will kill any bacteria that might have started growing while you were thawing the food.
How long does food last in the freezer?
Remember, food stored at 0°F is technically safe to eat indefinitely. But because food quality decreases the longer it stays frozen, the flavor of frozen food is a different story. For that reason, most freezer guidelines you see are based on when food will be at its peak quality, not when it will go bad.
If you have any questions on how long to keep food in your freezer, the USDA has a list of foods and their recommended freezer times. For example, the USDA recommends throwing out frozen chicken after 6-12 months in the freezer. The chicken is still safe to eat at 13 months, but it will likely have little to no flavor.
Be aware that fish and other seafood don’t refreeze as well as other common meats. If possible, try to only cook them once.
You can also check out our leftovers article for recommendations on how long to keep food in the freezer.
What about freezer burn?
When food gets freezer burned, it means its quality has been compromised. Even though it’s technically still safe to eat, it probably won’t taste very good.
If a food item has extensive freezer burn, you may just want to throw it away. If only a portion of the food is burned, you can cut away those portions and use the rest.
You can also follow these tips to help avoid freezer burn in the first place:
- Use packaging designed for use in a freezer. These bags and containers are usually thicker and are designed to protect the integrity of the food you put in the freezer.
- Remove excess air from inside the packaging before freezing. Freezer burn happens when the food comes into contact with oxygen.
- Let food cool before freezing it. Not only will this help prevent freezer burn, it’ll help keep foodborne bacteria from growing to dangerous levels while it cools in the freezer.
As a final note, food that has been in the freezer for a long time, especially if it has signs of freezer burn, is not likely to taste good on its own. But that doesn’t mean it’s only fit for the garbage can! Try using it in other recipes like stews, casseroles, chilis, etc. The other foods will help make up for less flavorful ingredients.
— Hailey Kate Chatlin