Breast milk is considered liquid gold and EVERY precious drop counts.

So you definitely don’t want to toss any out if you don’t have to! 

But what if your frozen breast milk tastes or smells bad?  There could be several reasons for this and not all of them require throwing out the breast milk. Let’s explore…

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What does normal breast milk taste like?

Freshly expressed milk tastes a bit like cow's milk, but more mild and slightly sweeter.

Many people say it tastes like sweetened almond milk.  The exact taste can change slightly depending on what foods you ate recently.

4 Reasons Frozen Breast Milk Tastes Bad

1. Spoiled Milk

Spoiled milk happens when breast milk isn’t stored properly.

You can tell if breast milk is spoiled by the appearance and the smell.  It’ll have a strong “off” smell and might have chunks in it, similar to when cow’s milk is spoiled.

When freezing breast milk the BEST way to preserve essential nutrients is to use glass containers. Not all glass containers can freeze without cracking, but these can! (and they’re perfect for breast milk)

2. Something in your diet

Chemical oxidation of breast milk might be the culprit if your breast milk has a metallic taste to it.  This is thought to occur from something in a mother’s diet such as eating too many polyunsaturated fats or drinking water with too much iron and copper in it.

3. Mastitis/Blocked Ducts

Does your breast milk taste salty?  If you’ve had mastitis, clogged ducts, or were engorged around the time of expression it can make your breast milk taste slightly salty. This is due to your breasts retaining more sodium and water when they’re swollen.

4. High Lipase

If your thawed, frozen breast milk has a sour, metallic, fishy, or soapy taste, it’s possible that the enzyme lipase is to blame.

All breast milk naturally has lipase in it because it helps break down the milk fats into smaller particles for baby to digest.

Some women have higher levels of lipase in their breast milk than others. When levels are too high, the enzyme continues to break down fat in the breast milk the longer it sits out, even after it’s frozen.  This leads to the breast milk eventually tasting bad.

If your baby doesn’t mind drinking the milk with high lipase, they can continue to do so because it won’t harm them.

But if they refuse to drink the milk because of the taste, you can scald the milk to deactivate future lipase activity.

Once the milk becomes sour, there’s no way to reverse the smell/taste. Scalding breast milk only works to deactivate lipase BEFORE it starts to break down the milk.

To scald milk:

Gently heat breast milk on low heat in a pan on the stove. (Do NOT boil.) Once the milk starts to bubble around the edges, take off the heat and cool quickly by placing the pan in a large bowl filled with ice water. 

NOTE: Scalding milk removes some immune-boosting components of breast milk so if your baby willingly drinks high-lipase milk, it’s best not to scald the milk.

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Related Article - 12 Things You Can Do With Leftover Breast Milk