Freeze Drying 101
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Freeze drying is an intimidating idea, but it is one of the easiest ways of preserving foods. It doesn’t destroy nutrients or flavor like other methods can, and it doesn’t require any pectin, salt, or other forms of preservatives. There are a few necessary items to begin the freeze dry journey.
First, choose the freeze dryer that suits the need. For a family of two, an extra-large is overkill. For a family of four, a small or medium is perfect. For a large family, or extended family, a large or extra-large is the best option. Remember that an extra-large will require a specific outlet, which may require a little electrical work. All freeze dryers require a dedicated outlet with absolutely no other items on the same circuit. Find a spot in a safe part of the home for the dryer. Make sure there is plenty of ventilation and the room temperature stays in the 50° to 75° F range. While the machine can run outside of these temperatures, it can cause it to work too hard and shorten its life. Using a small fan next to the vents can help with circulating the heat the machine adds to the room.
Harvest Right has a lot of different items that make the freeze drying experience easier and more fun. However, the basics are included with the dryer, and they are all that is needed to begin. The dryer package includes the dryer and pump, trays, mylar bags, oxygen absorbers, and an impulse bag sealer. One extra item that should be added is the silicone tray liners. They help release food easily and extend the life of the trays.
Once the dryer arrives, place it in its new home, set everything up, and let it sit for 24 hours. This is the hardest part of freeze drying. However, during the next 48 hours, read the manual thoroughly and put some foods in the freezer to dry when the initial steps are finished. After the first 24 hours are over, turn the machine on, and go through the initial setup process, outlined in the manual. Now, it is time for the bread run. Place regular bread on the trays, spritz them with some water, and run a complete cycle. This will remove the chemical smells of the manufacturing process.
Once the bread cycle is finished, defrost the machine. Touch defrost, follow the onscreen directions, and give it 1-3 hours, depending on the thickness of ice. Once it is defrosted, it is ready for its first real cycle.
The default settings are fine for every food, except candy. However, make adjustments and try different settings to see the results. For example, vegetables such as corn and green beans take between 16 and 18 hours to dehydrate, so a standard setting, with the default two hour extra dry time is perfect. Fruit can take up to 48 hours (or more) to completely dry, so setting a longer extra dry time is important.
To change the settings,simply touch the “customize” button on the opening screen, and change the settings as needed. Touch the default button to see the standard settings. My personal choice is to set the freeze temp down to -20° F, no extra freeze time, 125° F, and five hours extra dry time. The extra dry times gives a buffer to get to the machine when it is convenient.
Once the cycle has finished, release the pressure, and check the food for moisture. There are three ways to check for moisture. First is the touch and texture method. This is the least reliable. If there are any cold spots on the tray or food, the food isn’t fully dry, so it needs to have at least two more hours dry time. By eating a piece or two, the texture reveals whether the food is dry or not. If it is chewy at all, it is not dry. Fully dried food has the texture of the corn starch based packing peanuts. At the beginning, it is best to rely on other methods of testing.
The second method is a moisture meter. This is a simple, handheld device used in construction to test for the moisture content of wood. By placing the two prongs into the food, testing several places on each tray, it is easy to tell if there is any moisture content remaining. If moisture remains in a single piece of food, add two more hours dry time, and test again. This is cost effective and easy.
The third method is to purchase a scale that weighs to the smallest weight imaginable. Look for one that weighs down to at least the 1,000ths past the decimal (.000 or smaller). This is the most reliable, but also the most tedious method to ensure dryness. After the initial cycle ends, weigh each tray. Number the trays, and write down the weight. Rotate the trays, and add two more hours of dry time. Weigh again. If the numbers have not changed, the food is dry. If it has changed, add two more hours. Continue until the numbers do not change. This is especially helpful with foods that contain tiny seeds, which have a protective layer that is full of water that is very difficult to dry. The seeds can cause the food to soften and go bad in a few months.
Once the food is completely dry, package it. While canning jars are excellent for storing foods, the shelf life isn’t excellent. If stored in a cool, dark, dry place, canned freeze dried food can last up to 10 years. If it is stored in a similar place, but it is in Mylar bags, the food can last up to 25 years. Fill the bags with the food, add an oxygen absorber (see the Oxygen vs. Moisture Absorber article), close and seal. Make sure the seal is complete, then store. These bags can be stored in totes or barrels specifically designed for food storage. If using jars, include an oxygen absorber at the top, and either seal with a vacuum sealer, or wait for the packet to seal it, label and date the lid. Be sure to label the bags with the contents and date. Keeping an inventory on the storage container is also useful to help with future searches.
Freeze drying is fun, exciting, and useful. Preparing for the cold months, food shortages, high food costs, and the apocalypse is something that people should do. While the dryer itself is expensive, it will save the cost in just a handful of cycles. Almost every food can be dried, which gives endless possibilities. Check out other articles that share ideas, such as fruit, vegetables, candy, and soup base. To see a great list of foods that can be freeze dried, check out the Harvest Right website: https://affiliates.harvestright.com/2979.html
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