Q&A: Why does my frozen breast milk have a funny smell?

There can be a few reasons for the "funny" smell you are reporting. First, consider how and where you're storing your milk. Be sure that you are using bags specifically designed for storing breast milk. Also, be sure you aren't storing it next to foods that might have a strong odor.

Here are some more freezing tips to keep in mind:

• Make sure your freezer is cold enough: The Centers for Disease Control (CDC) recommend freezing milk at 5 degrees Farenheit in the freezer portion of a refrigerator.
• Do not store milk in the door of the freezer.
• Using glass storage bottles instead of plastic.
• Use milk within 24 hours of thawing. (It is safe to keep refrigerated for 5-7 days.)
• If transporting pumped milk from work, use cold packs and transfer to the refrigerator or freezer as soon as you get home.
• Wash all bottles and pump parts thoroughly.

Some moms report what they refer to as a sour or soapy smell or that the milk smells "bad'. If you are following all the storage guidelines, it could be caused by high levels of an enzyme called lipase (this breaks down the fat that is present in your breast milk). Dr. Ruth Lawrence, author of the book Breastfeeding: A Guide for the Medical Profession, theorizes that moms with an excess amount of lipase will have milk that gives of a strong smell. In many instances, right after a mom pumps her milk, this breakdown of the lipase begins and an excess of the lipase leads to the "funny" smell. Some babies may not mind the smell, but others may reject it altogether. Many moms have a hard time even feeding it to their babies fearing that is has gone bad.

Combatting the "Bad" Smell before Freezing
Scald the milk right after pumping to halt the breakdown of fats by lipase. When you scald milk, you bring it to the state JUST before boiling—approximately 180 degrees F. You want to do this on the stove top and not the microwave, as microwaving can destroy important properties in breast milk. Once you have scalded the milk, cool it and then freeze. If the odor in your milk has been caused by excess lipase, this should do the trick.