Does Freezing Kill Bacteria In Food? | Build a Stash

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Key Takeaways

  • Yes, freezing kills some bacteria found in food, but not all.
  • While freezing food below 0F can kill different types of bacteria, microbes, and mold, the harmful bacteria that cause your food to spoil will not be affected by freezing temperatures and you should not eat this food if it's rancid.
  • Freezing food is not a reliable method to kill harmful bacteria.
  • To prevent bacteria from spreading in food, store items in the freezer before they start going bad.

Freezing is one of the most reliable ways to secure the shelf-life of food items and prevent contamination, but does freezing kill bacteria in food?

Yes, freezing kills some bacteria found in food, but not all. While freezing food below 0F can kill different types of bacteria, microbes, and mold, the harmful bacteria that cause your food to spoil will not be affected by freezing temperatures and you should not eat food if it's rancid.

After extensively researching food storage preparation, I have gathered enough information to determine how to safely store food in the freezer. In this article, we’ll be taking a closer look at whether freezing food is a reliable way to kill bacteria.

Table of contents


Does Freezing Kill Bacteria in Food?

A key component of food storage safety is to prevent the spread of bacteria and reduce the chances of contamination. Traditionally, freezing has been one of the best ways to improve the shelf-life of goods to make them last indefinitely.

This storage method essentially keeps bacteria from spreading and contaminating your food. However, there is often quite a bit of skepticism regarding whether freezing actually kills bacteria that are already active in food.

Contrary to what some people believe, freezing does kill a lot of the bacteria in food - not all! Your freezer needs to be set to a temperature of 0F or less for it to be cold enough to kill most harmful bacteria. Freezing temperatures that hover around 32F will not suffice for inactivating bacteria present in your food.

Most importantly, freezing will not kill all bacteria in food. The bacteria that cause your food to spoil will still be active and will not be killed by freezing temperatures.

Is Freezing a Reliable Method to Kill Bacteria?

No, you should not rely on your freezer to sterilize food or kill bacteria. Despite the freezer being an ideal way to kill many of the active bacteria in your food and extend the shelf-life of products, this is not a reliable method for fully sterilizing food.

The reason for this is that the bacteria that cause your food to spoil can survive freezing temperatures. That is why you should never count on your freezer as a solution to sterilize your food.

Is it Safe to Eat Rancid Food After Freezing

Absolutely not! Your freezer is a great way to preserve food, not save it after it's gone off. Any food item that is rancid will not be safe to eat, even after being put in a deep freeze.

The freezing temperatures will cause the bacteria to become less active and slow down, essentially forcing them into hibernation. However, as soon as you thaw the food, the bacteria will begin to spread again.

The bottom line is that you should never eat bad food that has expired, and any rancid items should be discarded immediately. Your freezer will not save your rancid food!

How to Safely Thaw Frozen Food

When dealing with frozen foods, it’s important to understand that how we handle them can affect how much bacteria is present inside. This is particularly true when thawing frozen food items, as doing so improperly can accelerate the spread of harmful bacteria.

You need to ensure that you are thawing any frozen food items slowly, especially if they are already near expiration. For fresh foods that were stored properly early on, this may not be as big of a concern.

However, for older products, as well as meats and other foods from animals, you should approach the thawing process carefully. Thawing should be done slowly and in a controlled environment.

The best way to do this is to place your food items inside the fridge and let them thaw over the next 6 to 12 hours. A temperature of 40F is the ideal coolness for letting your food thaw optimally without increasing the risk of bacteria spreading.

How to Tell if Frozen Food is Safe to Eat After Thawing

Just because your food was in the freezer, doesn’t mean that it’s necessarily safe to eat. Given that your freezer is not a reliable way to kill harmful bacteria, you need to be careful when consuming food after it has thawed.

In addition, as mentioned above, the thawing process itself can potentially encourage the spread of bacteria if done improperly. At the end of the day, food safety is an essential part of storing goods at home and you should take precautions to prevent food poisoning. Be aware of the following signs to determine if your food is safe to eat after thawing.

Foul Smell

The first thing that you will notice if your frozen food is noticeably bad is a foul smell as soon as it thaws.

You may find that the smell is subtle and only detectable when you put your nose closer to the item, or it may be overwhelming and strong enough to clear out a room. Either way, if the smell is off and you are even remotely on the fence, throw away the food and don’t take any chances.


As food begins to decay, one of the early signs is that it starts to lose its original color. Depending on the food item that was thawed, the appearance can ultimately vary, but you should keep an eye out for any color changes.

Some color changes are natural after thawing, and I would recommend looking for additional signs. As always, if you have any doubts, it’s better to be on the safe side and throw it away.


This one should really be a no-brainer. Mold is a telltale sign that your food is rancid and needs to be thrown away immediately.

Slimy Texture

An early sign of food starting to go off is when you can feel a slimy substance start to appear on the surface.

As a general rule of thumb, I tend to throw out slimy items unless I am absolutely sure that they are safe to eat.

Bad Taste

While you can certainly identify a lot of the symptoms of rancid food, not all signs are so obvious. Food that is nearing its expiration date or just past it may be harder to determine if it's legitimately bad or not.

That said, if you end up cooking food and the taste is off, this could mean that it’s unsafe to eat. To prevent food-borne illness, I recommend not taking risks and throwing the food away.

How to Prevent Bacteria from Spreading in Food

The truth is that bacteria are already present in your food when you buy it. There are countless different types of bacteria in your food and a lot of them do not impact your health negatively.

Harmful bacteria appear in food when it’s mishandled and exposed to contamination. However, most of the food products in our homes end up going bad due to bacteria spreading over time, as the item gets closer to its expiration date.

The best way to prevent this from happening is to store your goods properly right after you buy them.

Keep Food in the Fridge

The fridge is where most of us keep our perishable foods and this is a great way to secure the shelf life of your goods. A food item stored in the fridge can last for considerably longer than at room temperature, given that bacteria does not spread as quickly in cold temperatures.

If you plan on eating the food within a couple of days or even a week, you can count on your fridge as an ideal place to keep most products.

Store Food in the Freezer Early On

While your freezer can kill a lot of the bacteria in your food, even after it starts spreading, it will not eliminate the harmful bacteria that cause your food to go rancid. Once your food is spoiled, you cannot save it by freezing it.

With that said, you can prevent goods from going off if you freeze food early on. If you know that you are going to have a food item in your fridge for longer than its predicted expiration date, the best thing that you can do is chuck it in the freezer right away, as this will prevent the spread of harmful bacteria.