I don't have a vacuum sealer, but I do keep my spare hops in ziplock bags in the fridge. I squeeze as much air az I can out before sealing. I'm AG now so I don't usually keep any grain around, except for this last brew which resulted in 13.2 extra pounds of grain due to the LHBS weighing in kg instead of lbs. The only fermentable I usually have on hand is a 3# bag of light DME for making starters. That also stays sealed in a zip bag.