покупать впрок(Stock up on foods that you normally eat on a day-to-day basis. Now I don't mean stocking up on things that can spoil, but you should definitely stock up on foods ... Alexander Demidov)
запасаться едой(также on groceries: Take time now to stock up on bottled water and nonperishable food (food that won't spoil) so you'll be prepared in case something happens.ART Vancouver)