Mountain House freeze dried foods are packed in airtight #10 cans. The cans are nitrogen packed, which means that the air has been replaced by nitrogen. Each can is coated with a protective enamel, including the lid. This enamel helps protect the can and the food within from moisture and air. The contents of the can are protected for many years. Mountain House foods have the longest shelf life available...up to 30 years! as long as the can is not opened or damaged. The contents are protected until you are ready to open and use them.