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How to tell if breast milk has gone bad – 5 surprising facts

Last Updated on June 6, 2021

Are you worried that your breast milk may have gone bad? Or are you just being proactive and want to know what signs to look out for?

Many moms freeze and store their breastmilk away for later use and whether due to incorrect storage procedure or something else, from time to time it can turn bad.

As a result, an important part of the breastfeeding process is being able to identify when your milk may have spoiled.


Recognizing Breast Milk Gone Bad

If you suspect your breastmilk may have gone bad or “spoiled”, then you should act on the safe side and not use it as it may cause a range of “bad breast milk” symptoms. With that said, here are some of the best ways to identify breast milk that may have spoiled and be no longer suitable to use.

Breastmilk Smell Test 

You may be familiar with the scent of your breastmilk and in general, this can be helpful in identifying spoiled milk. Similarly to regular dairy milk if it smells sour or spoiled, then it probably has gone bad and is not safe.

However, this isn’t always the case for frozen breastmilk since the freezing process can result in the milk smelling different to fresh breastmilk. It certainly shouldn’t smell spoiled i.e. sour and foul, but it may have a unique scent and this does not mean that it’s necessarily spoiled.

The best way to determine if your breastmilk does change its smell through the process of freezing is to carry out a simple experiment. Express some fresh breastmilk, freeze it for a few days and then thaw it out. If the process does result in the breastmilk taking on a characteristic scent then you know that it’s the result of the freezing process and not a result of it being spoiled.

Unfortunately, some infants will not take up this thawed breastmilk and you may need to warm your breastmilk prior to freezing. If you notice a more successful feed when using the scalded milk, it may be time to consider this as a long term strategy.

You Can’t Mix the Breastmilk

Breastmilk contains many components including minerals, vitamins, proteins, carbohydrates, and fats. This mixture naturally separates into fat and non-fatty parts, however, upon mixing it should return to a normal homogenous appearance.

If it does not mix back together and you see some residual “chunks” or “floaters” it’s often a visible sign that the milk has spoiled and is not safe to drink.

Taste the Breastmilk 

Similar to the “smell test” breastmilk that has gone bad will often taste rancid, sour and foul. Much like dairy milk upon tasting it, you can usually immediately identify whether the milk has spoiled. Therefore, upon thawing frozen milk, it’s a good idea to carry out the taste test before feeding it to your infant.

Check for Broken Seals 

The correct storage of breastmilk is essential as it prevents the milk from being exposed to the air and potential microorganisms. Therefore, if the seal of the bag or container you store the milk in is broke in some way the chance of it being spoiled is vastly increased. Therefore, it’s always advised to dispose of milk you suspect may be at increased risk of contamination.

How to Store Breastmilk Properly  

In order to ensure that breastmilk remains unspoiled and free from microorganisms and potential pathogens, you should store breastmilk appropriately. This involves using the correct type of container, being aware of appropriate storage periods and how to properly thaw milk that has been frozen.

Should You Store Milk in the Freezer or Refrigerator? 

You can store freshly expressed milk in both the freezer and the refrigerator. As you might expect, storing milk in the freezer will preserve it for much longer, so it’s a great way to create a stockpile of breastmilk.

Breastmilk stored in the fridge won’t last as long, but it’s a great way for short term storage and means you can avoid the process of thawing.

What Type of Container Should You Store Breastmilk in?  

Breastmilk is able to be stored in a wide variety of different containers and storage bags. The most important thing is to ensure you maintain a high level of hygiene, therefore prior to handling the milk and container of choice ensure you wash your hands thoroughly with soap and water.

Another factor is the type of material the container is made from. Although you can use plastic and glass, ensure they are designed for breastmilk storage. You will also want to avoid bottles with the recycle symbol 7 on them, which indicates they contain a BPA plastic.

While many people like to use breastmilk storage bags, many people point out that these can be more susceptible to tearing than containers made from tougher materials.

How Long Can you Store Breastmilk For? 

The storage times change depending on where you decide to store the breastmilk, which can include at room temperature, in the refrigerator or the freezer. As you might have guessed the colder the environment, the longer the storage time.

According to the Centers for Disease Control and Prevention, breastmilk can be stored for the following amount of time:

  • At room temperature (77°F or colder) for up to 4 hours.
  • In the refrigerator for up to 4 days.
  • In the freezer for about 6 months is best; up to 12 months is acceptable.

How Much Breastmilk Should You Store? 

Ideally, you should store breastmilk into an amount you will use in a single feed, as this will help you avoid wasting milk and save you time. Therefore, start by storing small amounts of breastmilk, typically this starts at around 2 to 4 ounces.

Also remember that freezing causes the substance to expand, so do not fill the storage container to the top. Some additional space will be needed as the breastmilk expands.

Don’t Forget to Label the Breastmilk Container 

In order to keep track of how long the milk has been stored, you will need to label the container with the date that the milk was expressed. Remember to use waterproof pens and labels since it’s likely that they will get wet especially during the thawing process.

Can You Add Fresh Milk to the Storage Container?

You should only ever add additional breastmilk you have expressed to the breastmilk you placed into storage on the same day. It’s also important to avoid adding freshly expressed milk immediately into the container containing frozen milk as this may cause it to thaw out.

Instead, place the freshly expressed milk in the refrigerator and once cool add it to the container containing the frozen breastmilk.  

Thawing Breastmilk Properly 

You can thaw out frozen breastmilk in two main ways, either in the refrigerator or by placing it in warm water. The method you will choose will depend on your circumstances, but planning in advance and thawing the night before is probably advised.

That way you will know you have milk ready for the following day and it’s just one less thing to worry about.

To thaw the milk out using warm water, you can run it under a warm tap or place the container in a warm bowl of water. Once you have thawed the milk out and it is brought to room temperature it should be used within 2 hours.

It’s important to remember that breastmilk should never be re-frozen and should be discarded after 24 hours.

Breastmilk Gone Bad

Do You Think Your Milk’s Gone Bad? 

It’s important to be aware of how to check whether or not your milk has gone bad and whether it is still safe to feed your baby. Thankfully, it’s usually very easy to identify spoiled milk, it’s a simple case of checking the smell, taste, color, and consistency.

If you do discover your breastmilk has spoiled, maybe it’s time to re-assess your storage methods. As mentioned above, factors including storage times, containers, amounts, and use by dates are all important points to consider.

Do you have any stories to share about breastmilk that went bad? Or any advice that you think may be helpful? We would love to hear them.

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