A freeze-dryer is a device used to preserve perishable items. Freeze-drying foods removes the water content from them and replaces it with a gas. Freeze-drying is a great way to retain the nutritional value, color, shape, and texture of foods. There are many different types of freeze-dryers that can be used to freeze-dry foods; however, most of them are extremely expensive. A less expensive option is to make your own freeze-dryer.
Purchase a styrofoam cooler, if you don't already have one. The size of the styrofoam cooler you need will depend on the size of the food that will be freeze-dried. The cooler should be small enough to pack the food in without a lot of extra space.
Place a layer of dry ice across the bottom of the cooler when you are ready to use the freeze-dryer. Do not put dry ice in the cooler if the homemade freeze-dryer will not be used immediately.
Set the food item to be freeze-dried on top of the layer of dry ice. Be sure not to stack food or bags on top of each other, they should be placed side by side in the cooler. Cover the items with a layer of dry ice and add another layer of food items to freeze-dry on top of the dry ice. Repeat this process until the styrofoam cooler is just about full. Make sure that the last layer is dry ice.
Place the lid on the styrofoam cooler and let it sit for about 30 minutes. Check the items that are being freeze-dried to see if they are frozen solid, if not put the lid back on the cooler and continue to check the items every 5 minutes. When the food items are frozen solid they should be removed and placed in a normal freezer until they are ready to be used. If the items have been vacuum-sealed prior to freeze-drying, they do not have to be placed in a normal freezer but can be stored in a pantry or food closet.