How can you tell if milk powders have gone bad?

[ScentsandMore]

I have some whole, buttermilk and honey powders in my freezer and have had them in there since the last co-op (2-3 months). How can you tell if it is still okay to use it in milk baths. Also, if it is that old, and I'm just now using it, will it cut the shelf life down in my milk bath or does the shelf life start once you put the milk powder in the milk bath? Thank you.

[HeavenScentU]

I know the ones in the store have a use by date. Can you check where the stuff was purchased on it's shelf life, but I don't think in 2-3 months time that your powders would go bad.