2. The dry ice method
You can also freeze dry food with dry ice. Dry ice lets all the moisture from your food evaporate quickly, so the whole process is much faster. Find a day when the humidity level is zero too, don’t try this method when it’s rainy out as the humidity will make it much harder.
You will need a pair of insulated gloves and a large container, about twice the size of the food that you want to freeze dry. Completely cover the food with dry ice and fill the container, use a 1:1 weight ratio (meaning 1lb of food should get at least 1lb of dry ice). DO NOT SEAL THE CONTAINER…it will explode.
Dry ice gives off a large volume of gas as it evaporates and it has to be able to escape. You can loosely put the lid on, or drill holes in the lid, but do not seal it. I just leave the lid up.
Once you can see no more dry ice left in the container, you know that the process is finished. This usually takes about 24 hours, or less. Once the dry ice is gone the process is complete.
Your container is now full of carbon dioxide and free of humidity. Do not take the food out until it is ready to be bagged. Use ziplock plastic bags to store the now freeze dried food, but make sure suck the air out as best you can to prevent moisture formation. Many people opt for vacuum packing devices or machines for better results, and I highly recommend you use them.
The goal is to ensure that no moisture is left or enters inside the plastic bag after the process is finished. You should seal it properly if you don’t want your efforts and your food to go to waste.