Good to know baking powder can be gotten aluminum free. I just checked the little can we have and it has aluminum in it. I don't use baking powder much at all, but it was interesting to note. We use straight baking soda more often -- recipe preferences I guess.

On the flour, I don't know why your idea wouldn't work. De-oxygenating is all you're doing, right? White flour or whole wheat? The latter doesn't store well at all.