Since 1995 - Non Profit Healthcare Advice

Spoiled frozen breast milk



I had a premature baby 3 mos ago and have been pumping and freezing. Now he is finally home and i am finding that alot of the milk has a soapy/spoiled taste and is separated. What could be wrong?? Help!!!!


Congratulations on having your baby home at last. Since breast milk is not homogenized, it is normal for it to separate with the cream (higher fat content) rising to the top. Simply swirl the bottle of milk gently before heating it to remix the contents.

The soapy, spoiled smell or taste you describe probably is due to “hyper” activity of the enzyme lipase, resulting in a breakdown of some milk fats. Enzyme activity appears to be greater for some women. Among those describing this, some also say they find stringy material in the milk, which may be the separation you refer to.

Have you been storing the milk in the freezer of a combined refrigerator-freezer model? It is thought that the self-defrost cycle of these models may contribute to the soapy smell. This may be one reason that guidelines for collecting and storing mothers` milk recommend 2-3 months as the length of time milk can be stored in the freezer (with a separate door) of a refrigerator-freezer combo.

If your baby is willing to take the milk, the changes do not appear to be harmful for a baby. Some babies reject such milk, and there isn`t anything that can be done about milk already frozen. If you are continuing to pump, you should be able to avoid this problem in the future by heating newly expressed milk to a scald (not boiling) right after expressing it. Then cool it quickly and freeze. This inactivates the lipase and stops fat breakdown. (Unfortunately, scalding won`t help milk that has already been affected.)

All the best…


Lawrence RA & Lawrence RM (1999). Breastfeeding: A guide for the medical profession (5th ed.). St. Louis: Mosby.

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