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Troubles with your breast milk?

What to do if you have issues with the taste or smell of stored breastmilk

Pumping and storing breastmilk is a great way to give your baby all the nutritional benefits of breastmilk even when you can’t be with them. Over time, you might start to notice that your stored breastmilk has a soapy or rotten smell. We understand if this alarms you at first. After all, you worked so hard to pump and store that liquid gold, and now you're wondering if it’s all for nothing.

Rest assured, this smell does not mean that your milk is rotten. Many factors affect the smell and taste of your breastmilk, including your diet, any medications you might be taking, and other biological factors that are out of your control.

The truth is, when you're breastfeeding, you don't know how your breastmilk smells or tastes because it goes directly to your baby. Often, your baby is accustomed to your unique flavour of breastmilk (similar to the amniotic fluid you shared with them while they were in the womb).

It becomes a more significant issue when your baby begins rejecting your "soapy" smelling milk. You might feel as though you’re failing your baby because they don’t like the taste of your milk, but that couldn’t be further from the truth. In fact, your milk is likely still okay for them to drink, and several remedies can solve whatever is happening to your stored breastmilk.

A baby hand on a pouch of breast milk
Handling precious breast milk in the right way is paramount.

What Causes Your Stored Breastmilk to Smell Bad?

A few things could be causing your breastmilk to smell sour, and it doesn't always mean that you need to dump your breastmilk down the drain.

Bacteria Growth or Contamination in Your Pump Parts

The first thing you’ll want to do if you notice your stored breastmilk is smelling a little “off” is to ensure all your pump parts and accessories are clean and that you’re following safe handling and washing procedures. Any little bit of bacteria in your pump can be transmitted to your freshly pumped milk and cause it to go bad. We cover proper cleaning procedures in our blog post about expressing and storing breastmilk.

High Lipase Activity

If your breastmilk is smelling a little soapy or metallic, it could be caused by high lipase activity. Let's start by saying that this doesn't mean your breastmilk is bad or that there's anything wrong with it. All milk has lipases, which are enzymes that aid in digestion and help your baby absorb all the great nutrients in your breastmilk.

· Ensures that the fat molecules remain well-mixed into the milk in a small, easily digestible form.

· Breaks down triglycerides to release fat-soluble nutrients.

· Releases free fatty acids to provide immunological effects.

· Protects against infection by intestinal parasites such as Giardia and Cryptosporidium.

You can clearly see that lipase activity provides countless benefits to the baby. However, lipase activity can become high in expressed milk when stored for a certain amount of time because it breaks down the fats faster. This gives the milk that distinct soapy or fishy smell, and why you can’t smell it in freshly expressed breastmilk.

If high lipase activity is to blame for that unmistakable aroma of your breastmilk, it’s still safe and completely nutritious for your baby. If they turn their head or push the bottle away because of the smell or taste, there are some things you can do to make your stored milk more appealing (we’ll get into that later in this article).

Chemical Oxidation

In other cases, rancid-smelling breastmilk can be caused by chemical oxidation. Chemical oxidation occurs when a breastfeeding or expressing mother consumes too many polyunsaturated fats or drinks water containing free copper or iron ions. Once this happens, you cannot give that breastmilk to your baby because it is no longer safe or healthy.

To prevent chemical oxidation, a simple change in diet will solve the issue. Avoid fish oil, old vegetable oils, some nuts like Brazil nuts, or other foods containing rancid fats. Drink bottled water or drink water from another source to reduce the effects of free copper or iron ions.

If chemical oxidation is causing the rancid odour in your breastmilk, the milk must be discarded and not given to your baby. Just a few simple diet changes will ensure that breastmilk expressed and stored in the future will not have this issue.

How Can You Tell What’s Affecting Your Breastmilk?

If you’ve checked your pump parts and storage containers and found them to be clean and sanitary, then you’ve already ruled that out as a possible cause of your odd-smelling breastmilk.

Identifying whether high lipase activity or chemical oxidation is the cause of the foul odour is relatively simple. All you need to do is smell your breastmilk immediately after you've pumped or expressed it. What does it smell like?

As an aside, breastmilk has a mild smell and a sweet taste, so it might not smell like anything at all. That’s a good thing.

If you notice that your freshly expressed breastmilk is smelling sour or rancid, it's likely chemical oxidation that's spoiling your milk. Dump that milk down the drain and adjust your diet as indicated above. Continue to check your breastmilk after you express it to ensure that your diet changes improve your milk's smell (and taste).

If it smells fine, store it as you usually do in the fridge or freezer and check the smell and taste over time. First, you might want to check every few hours, then every few days, and every few weeks (depending on how long you plan on storing the milk). Remember to follow the rule of 4s, which means you can store freshly expressed or pumped milk for up to 4 hours at room temperature or up to 4 days in the refrigerator. When you freeze expressed milk, using within six months is preferred, but it's safe for up to 12 months.

Doing this helps you pinpoint exactly when your milk starts to turn soapy or metallic. For some women, it can be a few hours, and for others, it can be weeks or even longer before high lipase activity affects the smell and taste of breastmilk. Knowing when your milk will change means you should try to serve it to your baby before that time passes.

However, if you notice that smell changes in just a few hours, there are a few things you can do to make your baby interested in your stored breastmilk.

What Can You Do to Make Your Breastmilk Palatable Again?

One quick and easy way to get your baby to drink soapy-smelling breastmilk is to mix it with freshly pumped breastmilk. This will add some sweetness back into the milk so your little one will enjoy drinking it again.

Another great option is to mix the stored breastmilk with solid foods (if your baby is old enough to begin eating solids). Adding some of the stored milk to oatmeal or baby cereals is a great way to mask the smell and taste while giving your baby all those nutrients in the breastmilk.

If your milk starts smelling and tasting off within hours, sometimes before you even get home from work, then you’ll want to try something called scalding. Scalding your milk prevents high lipase activity from affecting the smell and taste of your stored milk, no matter how long you plan to keep it in your fridge or freezer.

Scalding can only be done to freshly expressed milk, so if you’re pumping at work, you’ll need to heat your milk right away before you store it for later. You can use a bottle warmer to scald the milk, but a pan works best (just be sure you don’t warm your milk above 82 degrees Celsius or 180 degrees Fahrenheit).

To scald your breastmilk, heat it to the point where bubbles form but do not boil it. Boiling can rob the milk of valuable nutrients. Once bubbles begin to form around the outside, remove it from heat and cool it in an ice bath. This helps safely bring the temperature down before putting it in the fridge or freezer.

Research has also shown that lowering the pressure and speed of the breast pump can improve the smell of stored breastmilk.

If you find that your baby refuses your breastmilk because of its smell or taste, it can feel defeating. Remember that there's nothing wrong with you, this is entirely normal, and a foul odour doesn't necessarily mean that your milk is bad.

With just a few minor adjustments, you can continue to provide your baby with great-tasting milk that's filled with all the nutritional benefits your breastmilk has to offer.

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