Gross-Tasting Frozen Breastmilk

Archived Q&A and Reviews

I've been stockpiling breastmilk and it tastes pretty gross

September 2002

I've been pumping and freezing breastmilk since May in preparation for returning to work. Now I'm back at work and have thawed the frozen breastmilk, only to discover that it tastes pretty gross. Tastes stronger and more unpleasant than fresh breastmilk. My 6 month old son has only tried it once but he frowned and only took a couple of sips. Already he eats very little when I'm away and tanks up more at night. I don't want to put him off his new skill of drinking from a cup by serving an unpleasant beverage. My questions: What to do about the gross tasting breastmilk' Is it better to serve this or to supplement with formula as needed' Is there a way to freeze breastmilk so that it tastes better' (I've been using the Medela bags, not double bagged) Thanks!! Julie

Oh boy. You might have my problem. I couldn't store my breastmilk because (I found out after trying every storage system available and finally out of desperation contacting a lactation consultant) that I have high amounts of lipase in my milk, which causes it to decompose more quickly. (Lipase is an enzyme that breaks down fat.) I could store my milk for about 8-10 hours in the fridge, and then it got the funk. Forget freezing. The lactation consultant told me that I had the option of scalding it on the stove before storing it so as to de-activate the lipase. Of course, then you are de-activating a lot of other beneficial stuff too... not to mention the pain of having to pump THEN scald THEN store....! Anyway, that might be the issue with you too. Try different storage systems or whatever else people here might suggest, but know that you might be among the rare breed of women who has the high lipase thing going on. -- Ilana

I was very concerned with how bad my frozen breastmilk tasted (to me) that I spoke to my pediatrician about it. At first I thought perhaps my freezer wasn't freezing it well enough (which was not the case; the doctor said that if the freezer kept my ice cream hard with no evidence of thawing cycles, it should be just fine for breastmilk). Then I was worried that storing milk is a bit like making beer: you'd better have everything incredibly sterilized or it goes bad. In fact, there was something to this when I did a series of experiments. First, I made sure I always put the pump horns and the bottles and caps through the sterile dishwasher cycle or boiled them prior to every use (I had several sets of horns for this purpose). Second, I made sure that if I was going to freeze milk I froze it immediately. I found that some of the sour (but apparently not spoiled) taste came from sitting in the refrigerator for a day or two before freezing and that it tasted better if I froze it right away. When I did these two things religiously, I found that the frozen (and even refrigerated) milk had a less sour taste to it. However, in tasting the milk I found that it always acquired a ''slightly off'' (yes, ''gross'') taste after it spent more than about 6 hours in the 'frig, and freezing always made the milk taste strange to me. In my case, however, I didn't do these ''experiments'' until I'd already been feeding my son pumped breastmilk for several months (we started doing frozen breastmilk when he was 2 months old). He never seemed to mind ! And he never became ill. [I did throw away the older frozen breastmilk for which I had not put the bottles through the dishwasher or boiled them first to be safe, though.] So, I believe (and our pediatrician concurred in my case) that you can minimize the different taste by making sure everything is sterile before storage and by freezing right away but that storage and freezing necessarily impart some changes in taste and texture. While I did eventually start supplementing with formula when my son was 8 months old, he still preferred the strange-tasting frozen milk over strange-tasting formula until he got used to the formula. KB

I used the Medela bags to freeze my breastmilk and did not notice any odor problem. You might consider putting the full bags in a small box or bowl in the freezer and sprinkling some baking soda at the bottom, just in case the smell is coming from something else in the freezer. Liquids can easily take on odors of nearby foods. The baking soda will help neutralize smells.

As for supplementing, one of the things we were told in the ''breastfeeding and working'' seminar I attended is that you lose the benefits of breastmilk when you mix it with formula. If you plan to supplement, it's best to feed your child whole bottles of breast milk interspersed with whole bottles of formula. But mixing the two in the same bottle can kill the white blood cells that provide much of the benefits breastmilk affords. But, other than that, there's certainly nothing wrong with supplementing with formula. Gwynne

Have you tried thawing the more recently-frozen milk to see if it is the same way? It may be that you are one of the unfortunate moms whose milk simply goes bad more quickly than usual. (The typical recommendation is to use it in 3-6 months. If the ''gross'' milk is from May, but the milk from August is okay, you'll know you need to keep within the lower end of that range.) It could also be that the milk is picking up some smell/taste from something else in your freezer, in which case double bagging might help, or removing other things from your freezer might help. Or it could be that the milk was stored too close to the sides of the freezer or to the door, and thus was exposed to too much temperature variation. Keep the milk as much in the center of the freezer as possible. Also, if you don't double-bag, keep the bags in a plastic container or bowl of some sort. It protects the bags from tears and makes them easier to store in a good position.

It could also be that your son simply doesn't like to use a bottle or cup, if he hasn't previously used one much, and nothing at all to do with your milk. If that's the case, try varying the temperature of the milk, the position in which the caregiver holds him, and/or the type of nipple/spout.

Are you not able to pump *at* work? Most moms are able to avoid using frozen milk very much by simply using yesterday's pumped milk for today's bottles -- breastmilk can be kept in the fridge for 3 to 8 days.

If you have access to Usenet groups, I recommend It's a terrific resource for info and tips on pumping as well as any and every other question you might have about breastfeeding.

Good luck with the juggling act!

Holly (pumped daily for 7 months, until DS was over a year old)

Oh, I can relate to your frozen breastmilk tales. The night before I was returning to work I discovered that my stash of more than 50 bags of frozen milk smelled foul (similar to fish). Needless to say, I was devastated. Here are a few tips I learned:

-Never freeze milk on the freezer door. It doesn't get as cold as the back of the freezer.
-Double bag if possible. Breastmilk is very prone to picking up odors, or at least mine was.
-I found that I couldn't use milk that had been frozen for more than a couple of weeks. If you freeze in a deep freeze, it's supposed to last 6 months.
-La Leche League books and website will have better tips on freezing. Check them out.
-We ended up supplementing 1/2 formula and 1/2 milk pumped from the previous day. My daughter weaned at almost 8 months because she loved the bottle so much and I couldn't keep my production up but she finished the first year on formula and now enjoys soy milk. She's been very healthy but I would have gladly continued to breastfeed had she been interested. Good Luck! Linnea

Not sure what your gross is but mine was a soapy sour taste. I did some research and found that my milk has an excess fat enzyme that has been linked to sour tasting frozen milk. I tried the recommendation of quickly heating it, bringing it to the point of just about to boil then chilling immediately and freezing in medela bags. It's not fun and I don't know how much nutritional value is left after heating. I went back to work part-time at 8 months and continued to pump 2 bottles a day for our daughter until she went on cows milk at 12 months. She was also a very picky eater and fell off the charts for weight at 9 months. I'm happy to say that she is 20 months, incredibly bright, healthy, eats a wide range of foods and still breastfeeds 2 times a day. jeannine

Hi there. I have the same problem, and I've found that there are many possible reasons and many possible solutions. I'm sure you'll get a bunch of them here. I found good advice in the ''Nursing Mother's Companion'' book (the bible!!). Now I chill the milk in the fridge first and then freeze it, double bagged, not on the door. Good luck! Icky milk mommy too

I discovered that I had the excess lipase problem that other people mentioned after my baby had been refusing to drink from a bottle for a couple of months and I finally tasted it -- YUK -- like metal! Here' s how I figured out it was an excess of lipase (an normal enzyme that breaks down the fat, but some women have excess -- it affects the taste but not the nutritional quality). My freshly pumped breastmilk tasted fine. I split a freshly pumped amount of milk into two portions. I scalded one of the portions and left the other untreated. For each of these treaments, I further split into three portions -- one sat on the counter, one went in the fridge, and one in the freezer (so that I had one scalded and one unscalded in each storage method -- room temp, refrigerator, and freezer). It was definately the lipase problem, because the scalded milk tasted perfectly fine no matter how it was stored. The unscalded milk tasted awful (within one hour at room temperature, a few hours in the fridge, and after being frozen overnight and thawed). Some people recommend refrigerator storage, but this didn't work at all for me. I did find that the easiest way to deal with my problem was to microwave the milk briefly before freezing. Not to boiling, just until it's hot to the touch. This is effectively the same treament as stovetop scalding, but a lot more convenient. For my very wimpy microwave, this was about 1 min. for 4 oz. of breastmilk. I know that ''do not microwave breastmilk'' is a mantra out there because you will damage or destroy the beneficial antibodies. However, in this situation, the purpose is exactly to heat-inactivate the lipase enzyme (too bad we can't selectively inactivate only some enzymes). In any case, scalded breastmilk still retains all the wonderful nutritional qualities even if some of the immunological benefits are diminished, and it's better than having baby refuse to drink the breastmilk at all. Marguerite

Just thought of something that might be going on with your milk: do you have a nice, modern, self-defrosting freezer? If so, keep your breastmilk at least an inch from the sides, back, and door of the freezer, or it could defrost and refreeze everytime the freezer goes through a defrosting cycle (which I think is pretty often). Karen

It's been nine years since I did this, but I was told (by the nurses at the hospital) to only save breast milk for two weeks so I never had any milk in the freezer older than that. I'd put the new bottles in the back and use the oldest first. That could be the reason it doesn't taste so good. Also, I stored it in glass bottles which made it easy to heat up. anon