sour breast milk?... can't figure out why

[panda18]

My DS is almost 3 months old and we've had almost every nursing problem you can have. I've needed to pump and feed him due to incorrect tongue motions which caused me pain as well as thicken his feeds due to silent reflux and aspirating.
We've had no problems with pumped milk until today. Thankfully we're nursing more which means I have a lot more in my fridge. I usually bottle feed him first thing in the morning because I pump really well then. I prepare the bottles with xanthan gum before bed and leave them out for when he wakes up. This mornings bottle stunk horribly. I thought that maybe it was out too long since it was longer than normal. But then I prepared a bottle at 7 and two hours later after sitting out it stunk horrible too. I had to dump 11 ounces.
I'm not sure what's changed. I've been able to leave breast milk out in our house for up to 12 hours without any problems. I've heated it to add the xanthan gum and to get all of the hind milk from the storage bottle into the feeding bottle and then put the bottle back in the fridge to reheat later when it's time for him to eat. No problems until today!
I thought maybe my bottles aren't clean enough. So I steamed cleaned and boiled, then it happened again this afternoon and to a bottle that I just heated and added xanthan gum too.
So, the only last option is that the xanthan gum may be bad? Is that possible?
Does anyone have any ideas?

[mommy24babes]

Your milk probably isn't bad. Most babies dont seeem to mind it.
I had this issue a few times.

Check this out

http://kellymom.com/bf/pumpingmoms/m...expressedmilk/

[Ummsamiyah]

Leaving milk out for 12 hours is way too long. FYI

Sent from my iPhone using DS Forum.

[lilmomma83]

It could be lipase.. I doubt it is bad if it was in the fridge and your baby might not even mind it.

I leave milk at room temperature all day and occasionally overnight also...the storage times at various temps are definitly guidelines which vary from mom to mom.

I had lipase issues with my second baby and not with my first or third...I know sometimes moms scald milk right after pumping and that is supposed to reduce/prevent it - I've never tried though.

[TinaDeanette]

Sounds like lipase! Evil evil lipase.