Question:
I work at a small rural hospital in beautiful NW Montana, and lead a Mother/Baby Group weekly. I get a lot of breastfeeding questions, and one which has come up more than once recently, and which I have not been able to find an answer for is about breast milk that has been frozen and then thawed to use when the mom has to work. The baby will refuse to drink the thawed, warmed milk, supposedly because of an enzyme, or something similar, in the milk which makes it tastes bitter. I reviewed the mother’s procedures for storing the expressed milk, and then how it is thawed and warmed, and she seems to be following the correct procedure. I have never heard of this before recently, and now I have had a couple of moms ask me about it. Can you shed any light on this for me, and is there any solution to it?
Thank you so much,
Debbi Foss, RN, Lactation Specialist
Answer:
No one really knows how many mothers encounter a foul smell in their stored breast milk. The breastfeeding literature does not provide much help because the problem has not been well studied. Lawrence and Lawrence mention the changing flavor of stored milk in the 6th edition of Breastfeeding: A Guide for the Medical Professional (pg 781). They speculate that “rancid” or “soapy” smelling milk results from changes in the lipid (fat) structure of milk. Sometimes freezer burn contributes to foul odor or taste, but there is a theory that some women have more lipase activity than others. The enzyme lipase breaks down milk fats. Excessive lipase activity may cause the milk of these women to smell bad after even short periods of refrigeration or freezing. Some infants reject this milk; others do not seem bothered by the altered taste and smell.
The only solution offered is to advise these mothers to scald (not boil) the milk after pumping and before storing. Scalding inactivates lipase and stops the process of the excessive fat breakdown.
Kim Updegrove, RN, MSN, Clinical Director of The Mothers Milk Bank at Austin, states that she and her staff occasionally encounter smell changes in some batches of donated human milk when it is thawed prior to pasteurization. Donor milk is always bacteriologically screened. It is reassuring that altered smell in these milk samples has not revealed contamination or “spoilage.” Kim pointed out that the pasteurization process used in milk banks also deactivates the lipase activity in the milk.
The good news is that this milk is safe to consume. However, foul smell and bitter taste worries mothers and care-givers alike. It becomes a big problem if the baby rejects it. Scalding, while effective, creates extra work, especially for employed mothers. In our opinion, the issue of flavor and odor changes in stored milk cries out for more research. What a study this would make!
