I remember a couple of years ago returning with the remaining half bag of DD coffee. When we opened the checked bag the pressure difference had sucked out all the coffee and distributed it around the suitcase...made for some needing to be washed coffee smelling clothes. Not a major issue but into the baggie it now goes .......

I should have known 'cuz when we arrive the bag of coffee is like a solid, wrinkled brick after having all the air sucked out