Can powdered milk go bad? I've been using it for cooking about ayear, now. But, I put some in my coffee last week and it tasted pretty nasty. I don't know if I'm just not used to the taste, or if it is too old. It has been stored in an airtight container, but has been in there awhile.
Usual shelf life for powdered milk is one year for using it for any form of drinking, if it has been kept in an airtight container, in a cool, dark, dry place. It can still be used for baking after that time. If it is powdered whole milk then the shelf life is much shorter because the milk fat will go rancid.