Sour expressed milk?

[Pinchypants]

Morning! I don't know if I'm being paranoid but I've sniffed and tasted my expressed milk after DD left most of the bottle, and to me it seems really sour! I don't know why this would be or if it is actually true. I don't think my milk has tasted like this before. Anyone know what's going on?

I express a couple of oz every day so my six month old DD's grandparents can give her the 11am feed from a bottle twice a week when they come over to look after her while I work in my home office, and also to mix with cereal for breakfast. I store the expressed milk in the freezer immediately and defrost it quickly.

Any thoughts much appreciated!
Pinchy xx

Not sure if it's the same thing, but this thread might help?

I've never had this and I have tried the odd drop when it has dripped, as it were. But isn't BM supposed to change flavour?

Ooh JackieNo thanks a million for the link - that enzyme might be the problem. Will try scalding the milk tomorrow morning before expressing. I couldn't believe milk would go bad that quickly and this is reassuring.

Hope it works, pinchypants.

Have just read all the stuff on excess lipase in expressed milk on La Leche League website - have no idea why I haven't seen the website before, it's a mine of brilliant info and I am now quite excited about scalding my milk before storing tomorrow. Luckily there's not a big stash in the freezer - it's heartbreaking chucking out milk that's taken hours to express! Fingers crossed no more sour icky milk!
Thanks again for all your help - would be having a major crisis of 'my milk's not good enough' if it weren't for you lot.
Pinchy xxx