lipase issue only after freezing? kinda freakin' out!

[patronus]

my lo is 10 months old. she's in childcare and has always taken a bottle well.  for the last couple of weeks she's only been drinking about half of each bottle and it's been tough to get her to take that. i assumed it was because of an ear infection she was getting over and the fact that she was cutting a tooth. she has been nursing just fine.

i've got a huge freezer stash and thawed milk for the first time yesterday to send to childcare today (because of the holiday i hadn't been pumping).

well, she was hard to feed again so i tasted a bit of it and it tasted horrible! it was that soapy taste. i just froze this milk last week and it wasn't old when i froze it.

seems like lipase, but as far as i know it's never been an issue with fresh milk, even if i push it to about 6 days past pumping. but i don't taste my milk regularly because she's always taken it just fine.

i started to freak that my whole stash was bad and so i thawed milk from 4 months ago and tasted it. it tasted soapy too. AGH!!!!!!!!!!

any clue what's going on here?

could my milk only go "bad" only after it was frozen?

has it always been lipase-y? if so, why is she just refusing it now?

i donate my milk to the local milk bank so now i'm worried about that. will they still take it if i've identified a lipase issue? i've already donated 2 gallons!

[prothyraia]

No advice here, but my frozen milk always tasted off.  From the fridge was fine.

[CheriK]

Yes, it's common for high lipase to only cause a soapy taste when freezing the milk, although spending a long time in the fridge can also be an issue for some moms.  Just depends on how much lipase you have in your milk.  Lipase remains active despite freezing, which is why it gets worse when the milk is frozen.  The milk isn't bad, though, despite the soapy taste, and some babies don't care.  My youngest never minded, although I thought the milk tasted awful, and for whatever reason it wasn't a problem with my older two.  Milk banks don't reject milk due to high lipase; they frequently pool milk anyhow, so it would be diluted and unlikely to bother the baby receiving the milk.

Do you usually send fresh milk for her?  This might be why it's never been a problem before.  I wonder if you might be right about why she was only taking part of a bottle, and it's just coincidence that you discovered the high lipase now.  You might try to offer her a bottle of the defrosted milk after she gets over this illness; maybe she will accept it just fine.  Or if she won't accept it "straight", you might try mixing frozen and fresh milk to dilute the flavor.

If you plan on continuing to freeze milk and the soapy taste does bother her, you can scald your milk as soon as possible after pumping to stop the lipase action.  I have heard a couple reports (anecdotal) recently that high levels of DHA in your diet can increase lipase activity in milk.  So if you're taking a fish oil or other DHA supplement (some prenatal vits contain this), you might try stopping it and see if that makes a difference.  And some moms believe that rinsing their pump equipment and storage bottles in distilled water to avoid heavy metals also helps, as does using phosphate-free dishsoap.