Re: oily warmed previously frozen milk
The reason tasting it might be in order is because of possible excess lipase. Lipase is an enzyme that breaks down the fats in breast milk. It won't affect fresh milk because it takes time for lipase to work. But sitting in the freezer for a month or more... You get the picture.
I don't know that lipase would cause milk to look oily, though. It may be that heating the milk in warm water rather than in the fridge simply de-emulsifies it... I'm thinking about this olive oil and vinegar salad dressing I buy. If you leave it on the counter for a while, the oil floats to the top of the bottle. But leave it in the fridge for a while, and the dressing stays mixed.
Basically, if proper storage guidelines have been followed and the milk tastes okay... Then it is okay, even if it looks a little odd. Just swirl the bottle gently to recombine the separate elements.
I totally get not wanting to taste it! I wouldn't want to, either. But if it's good enough for your baby, it can't be too scary, right?
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