How does a freeze dryer work? Learn how to freeze-dry food at home when investing in a freeze-dryer to significantly extend the shelf life of food.
My husband and I own 1/3 acre smack-dab in the middle of a small town in Wisconsin. Unfortunately, in our small town, we have only one daycare facility that’s licensed and accepts children under 2, so I left my career in logistics to stay home to raise our children. Being a single-income family didn’t come without its difficulties! However, using our land to create an urban homestead has alleviated much of the financial stress.
We have two apple trees (with plans to expand this year) and 14 raised garden beds, with plenty of yard left for the kids to play! We also have our house on a bidirectional meter with 33 solar panels and a backup system for potential power outages.
Outside of solar panels and gardening, I focus on food preservation to boost our savings. I advocate for safe canning but also enjoy other methods, such as dehydrating, freezing, and freeze-drying. The ability to preserve food allows our family to grow our crops in large quantities or shop local sales and buy in bulk to save money.
I source a lot of our food locally via friends, neighbors, and farms. Even in town, we have a few neighbors with beautiful fruit trees and grapevines. Two years ago, we noticed that a neighbor down the block had a bountiful cherry tree that wasn’t being picked. I reached out to her, and she told me to take whatever I wanted – she does seasonal work and isn’t home when it’s ready. So, we prune and tend the tree and then bring her cherry jelly and cherry limeade in exchange for allowing us the privilege of picking her cherries. It’s been more than 10 years since I’ve bought a single jar of jelly! Another neighbor down the road gives us free grapes (5 to 15 gallons a year), which we use to make grape juice for our kids. So, although we only have 1/3 acre, having neighbors who specialize in certain crops allows us to focus on other items and save space, time, and money.
Freeze-Dry This, Not That
Having access to large amounts of food all at once requires me to be able to preserve it for the long term, and freeze-drying offers an exponentially longer shelf life in comparison with other preservation methods – 25 years. Another benefit of freeze-drying is that it maintains nearly all the nutritional value of fresh food. Other methods of preservation, such as canning and dehydrating, use high temperatures that destroy some of the food’s nutrients.
But the preservation method I choose really depends on the item I’m looking to put up and the length of time I want to store it. Broccoli, for example, can’t be safely canned because of density issues, which leaves you with dehydrating, freezing, or freeze-drying. Our freezers are full to the brim with beef, venison, and chicken, so if items can be freeze-dried or canned, those are my preferred methods. A few foods just don’t do well in a freeze dryer. These are typically more oily foods: peanut butter, chocolate, butter, honey, jam, jelly, and syrup.
Other foods are perfect for freeze-drying; here are my favorites.
- Spinach. I blend it into a fine powder and sneak it into all of my kids’ foods for a nutritional boost.
- Banana slices. Pro snacking tip: Use them as a “chip” and dip them into vanilla yogurt.
- Chicken noodle soup. Just add hot water, and it’s ready to eat in less than a minute.
- Mashed potatoes. We harvest potatoes from our garden to make mashed potatoes the way we like them, and then we freeze-dry the mashed potatoes. This creates instant mashed potatoes – just add hot water and it’s ready to consume.
- Cayenne peppers. My husband uses a ton of cayenne pepper powder, so I grow many peppers and make the powder myself to avoid having to buy it from the store. Freeze-dried cayenne pepper powder is more potent than store-bought, so less is more. However, because it’s freeze-dried, the flavor of the pepper is also richer. You get to taste the pepper before the heat kicks in!
- Yogurt. I make my own yogurt melts and yogurt bites for my kids. If you want to get fancy, you can make your own yogurt, flavor it with freeze-dried fruit powder, and then use a piping bag or molds to create small bite-sized pieces.
- Jell-O. Yes, you can freeze-dry Jell-O! It holds its shape too; try fun molds, such as hearts or skulls.
- Watermelon. This is my kids’ favorite; it tastes like cotton candy. But it takes a long time to process, and I highly suggest removing the seeds first.
- Eggs. This may seem bizarre, but you can freeze-dry eggs. Chickens typically lay a lot of eggs in summer and produce less in winter, so this is a great way to store eggs for winter. I freeze-dry raw beaten eggs, which allows me to use them for baking or cooking.
- Zucchini bread mix. I freeze-dry all the wet ingredients for my zucchini bread. Then, once I’m ready to bake, I add the dry ingredients and the water to reconstitute the freeze-dried ingredients. Mix and bake!
How Does a Freeze Dryer Work?
Often, freeze-drying and dehydrating get confused, as the processes seem similar, but they’re vastly different. Dehydrating involves heat to remove water from foods through evaporation, while freeze-drying uses a process called “sublimation.” Sublimation, in simple terms, is the conversion of a substance (water) from a solid state to a gaseous state without it passing through a liquid state. Two major factors determine what phase (solid, liquid, or gas) a substance will take: heat and atmospheric pressure. Freeze dryers freeze items, reduce the pressure within the chamber, and then add heat so the frozen water is sublimated.
Freeze-Drying Financials
Owning a freeze dryer is an investment, as they’re quite expensive. So, how much does it cost to run a load, and how long do loads typically take? Cost and time both have variable factors – cost is dependent on the cost per kilowatt-hour (kWh), where you reside, and possibly what season (winter versus summer); and time is dependent on how much water an item contains. The freeze-drying process typically takes between 20 and 40 hours to complete. Food type and quantity will affect the freeze-dry cycle. Foods with less moisture, such as meat, peas, and corn, dry quickly, while squash and watermelon can take longer. The thickness of the food slices will affect the cycle time too. I’ve had watermelon take upward of 72 hours.
A small-to-medium-sized freeze dryer draws an average of 9 to 11 amps (990 to 1,210 watts) of power per hour, which means a freeze dryer will cost an estimated $1.25 to $2.80 per day, depending on power costs in your area. I stuck a meter on my freeze dryer that let me monitor kWh and cost over the course of a month. While I did have a few days where I didn’t run it, the monthly cost was $34.31. Pre-freezing food before freeze-drying can save you money by reducing the amount of time and energy your freeze dryer needs to spend bringing the food down to the necessary freezing temperature, essentially making the freeze-drying process more efficient and lowering overall energy usage.
If you have littles like I do, freeze-dried yogurt bites and freeze-dried fruits are a hot commodity. Buying them from the store gets so very expensive. Let’s say you have your own apple tree. How long would it take just processing apples versus having to buy them to pay off a medium freeze dryer? A local major retailer sells freeze-dried apples for $2.61 per ounce. Freeze-drying one load of apples yielded me 21.2 ounces. Had I bought that amount from the store, it would’ve cost $55.33. Freeze-drying the apples took me 45 hours, and if I assume the highest cost in electricity at $2.80 per day, the electrical cost would be $5.25 – a savings of just over $50 per load. I used canning jars for short-term storage, so there was no Mylar bag cost or oxygen absorber cost. A medium freeze dryer after tax is roughly $2,600 to $2,900. It would take 53 loads of apples to pay off the machine. That means I could “pay off” the machine after about 113 days of freeze-drying apples if I also consider the defrost period of 4 to 6 hours between each load.
Another way many owners of freeze dryers offset the cost of the machine is to sell freeze-dried products or offer services locally and start a small business. However, my advice (as someone who has taken this route) is to check with your state law to make sure you’re properly licensed. In Wisconsin, freeze-drying doesn’t currently fall under cottage law (which allows individuals to sell baked goods made at home) and must be done in a state-inspected commercial kitchen. This is because freeze-drying can preserve bacteria present in the food you want to preserve, rather than killing it, as baking does. Even some temperature-controlled products (such as dairy and meat) made in a commercial kitchen can’t be sold without additional verification and product testing to ensure product safety.
Regardless, our urban homestead has allowed us to embrace a simpler, more self-reliant way of life. On just 1/3 acre, we’ve managed to grow our own food, harness solar power, and preserve what we harvest to save money and reduce waste. Freeze-drying has been a game-changer, helping us make the most of bulk foods and extend their shelf life while keeping the nutrition intact. It’s also a joy to connect with neighbors and share resources, like trading cherry jelly for access to a fruit tree. This journey hasn’t always been easy, but it’s been worth it – teaching us to work with what we have, care for the environment, and pass these values on to our kids.
Alayna McDonald is a mom, a modern homesteader, and a math major. She likes running the numbers and saving money. When she’s not gardening or preserving food, she loves to game, travel, and hang out with her horse.
Originally published in the April/May 2025 issue of MOTHER EARTH NEWS and regularly vetted for accuracy.
