Freezer burn is caused by air, specifically cold, dry freezer air, coming into contact with food. Think of vacuum sealed meals versus a plastic container half-filled with leftovers: the air trapped inside the container causes food to taste stale while the vacuum sealed food is protected from drying out. The same goes for ice cream. Protect the ice cream from air as you eat your way through a carton and you'll also safeguard against freezer burn. Yum!