Freeze-drying is one of the fastest-growing methods of home food preservation, and as more people get into freeze-dried food, there are bound to be questions about the process.  Don’t worry; I’ll walk you through everything you need to know about freeze-drying food at home.

Food preservation is one of my main passions, and we use just about every method under the sun, both historical and modern.  We love canning, both pressure canning and water bath canning, as well as salt curing, fermentation, dehydration, and cheesemaking. 

When the first home-scale freeze dryers were released in 2014, I just couldn’t wait to try them out.  They’re expensive, so I waited a few years to see how well they worked and read freeze-dryer reviews to see if they were worth the money.

Everything I read said that they were easy to use and well worth the investment, so last year, we finally took the plunge and bought a Harvest Right Freeze Dryer.

I’ve been running that baby hard for the past year, and it’s well worth it for my family.  They are easy to use, but there is a learning curve, as with anything. 

We absolutely love our machine, and I’m going to take you through everything you need to know about freeze-drying food at home.

Our own freeze-dried raspberries.

Why Home Freeze Drying?

Freeze-dried food has existed since the early 1900s, but home freeze-dryers are a relatively new way to preserve food at home.

Since home freeze dryers came out in 2014, home freeze drying has become more popular and more affordable each year.  When they were first introduced, the smallest model was around $5,000; now, they’re around $2,000.  With inflation and the cost of materials these days, the cost will not likely go down too much more.  They’re still expensive, but you can return the investment in less than a year with regular use.

If you’ve tried freeze-dried food, you know that the quality, flavor, and texture are all much better than dehydrated food.  The food lasts much longer with a shelf life of 20 to 25 years (as opposed to 1 to 2 years with dehydrating).

Freeze-dried food is lightweight and portable but rehydrates to the same flavor and texture as the original food.  You can freeze dry almost anything, including milk, eggs, meat, fruits, vegetables, and whole-prepared meals.

Since freeze-dried food maintains more nutrients than any other food preservation method, it’s also increasingly popular with the health-conscious.

Some of our more exotic homegrown fruits after a test batch in the freeze dryer. Including: Husk Cherries, raspberries, wild blackberries, alpine strawberries, blueberries and red currants.

How Does Freeze Drying Work?

Home freeze-drying works on the same principles as commercially freeze-dried food, and the machine automates most of the steps.  After you prepare the food and place it on the trays, they’re loaded into the machine.

Once inside the freeze-drying chamber, the machine drops the temperature to around -30 to -50 F.  (This step is faster if you freeze the food first in a regular home freezer, but you don’t have to.)

Once the food is at temperature, a vacuum pump drops the pressure inside the chamber.  Now everything is at a very low temperature and very low pressure.

Next, a small heating element built into the tray rack gently warms the food on the trays so that it’s a bit warmer than the ambient temperature.  That tiny amount of heat inside the vacuum chamber is what kicks off the drying process. 

When pressure is very low in a vacuum chamber, the liquid inside the food goes through a process known as sublimation, where the ice goes directly to water vapor (without becoming a liquid).

These racks are where you place the trays inside a freeze dryer. They’re attached to a small heating element, so they can be gently warmed to kick off the sublimation process while the chamber around the food stays about -40 F.

The ice crystals more or less just leave the food right into thin air inside the freeze dryer.  That same water then re-freezes on the chamber’s walls and stays there.

The food holds its shape (and texture) through the freeze-drying process because the ice acts as a scaffolding inside the food, and then it just sublimates off. 

Freeze drying removes around 98% of the water in food, effectively stopping spoilage and stabilizing freeze-dried food for 25+ years (if properly packaged).

Choosing a Freeze Dryer

Since home freeze dryers are relatively new, Harvest Right is the only brand that’s made and sold for home use.  Still, they have a number of options to choose from, so it can be tricky to find the right freeze dryer for your needs.  (As of spring 2023, there is one other brand that was just released called “The Cube,” but it’s considerably more expensive than Harvest Right, and little is known about this one, given it’s only been on the market for a few weeks.)

For home use, your main decision points are around the freeze dryer size and vacuum pump type. 

Freeze Dryer Size

The size choices include:

• Small – Sized for 1 or 2-person households, this unit is ideal for small batches.  It can handle 4 to 7 pounds of fresh food per batch, giving you about 1 to 1 1/2 gallons of prepared freeze-dried food per batch.  It runs on standard 110 electric and a regular household electric plug.
• Medium – The best freeze dryer for most small families, the medium can handle 7 to 10 pounds of food per batch, giving you about 1 1/2 to 2 1/2 gallons of freeze-dried food per batch.  It runs on standard 110 electric and a regular household electric plug. 
• Large – Perfect for larger families, or homesteaders who grow much of their own food at home, the large freeze-dryer can handle 12 to 16 pounds of food per batch, resulting in 2 to 3 1/2 gallons of freeze-dried food per batch.  This one also uses standard 110 electric, but you must install a special NEMA 5-20 plug on a dedicated 20 amp circuit.
• Extra Large – The extra large freeze dryer holds about double the amount of food as the large, and it’s truly a semi-commercial freeze dryer.  This one’s good for anyone hoping to make a business out of selling freeze-dried food, and there is quite a market for it online and at farmers’ markets and craft fairs (especially freeze-dried candy).  It’s also good for huge families, small farms, or communities to share.  It can handle 30 to 35 pounds of food per batch, producing 8 to 10 gallons of freeze-dried food.  Like the large model, this one also uses standard 110 electric, but you’ll need to install a special NEMA 5-20 plug on a dedicated 20 amp circuit.

We chose a Large freeze dryer because every single discussion group I could find recommended going with a size bigger than you think you’d need.  The biggest regret people had was getting one that was too small, and many devoted freeze-dryer users actually ended up getting a second freeze-dryer and setting it up right next to their first one.

We have a family of 4, but we also homestead and grow much of our own food.  I’m a passionate home canner, putting up at least 1,000 jars of home-canned goods yearly.  This isn’t our first food preservation rodeo…

For us, a large freeze dryer is just right.  It’s allowed us to put up whole meals and huge batches of my children’s favorite freeze-dried strawberries.  It can hold around 100 eggs per batch for freeze-dried eggs, which is a lifesaver when our hens lay heavily each spring.

Freeze-dried eggs in silicone trays inside our freeze dryer.

We still do just as much canning as before, but now we can preserve even more food with our freeze dryer.

For most small families that are not growing huge gardens, a medium freeze dryer is the right choice.  For empty nesters or families of just 1 or 2 people, go with a small freeze-dryer.

Conversely, if you’re hoping to put up enough food to feed a family or start a freeze-dryer-based business, go with an extra-large model. 

(Freeze-dried candy is a huge hit on Etsy, as are freeze-dried dog treats.  Selling those online or at small markets is a great way to make back the purchase cost of a freeze dryer.)

Freeze-dried skittles and other candy are especially popular on etsy.

Freeze Dryer Vacuum Pumps

There are two types of freeze-dryer vacuum pumps currently for sale, and they differ in both price and maintenance schedules:

• Premium Pump – Included with the freeze dryer, this pump is a dependable unit that gets the job done.  You’ll need to filter the oil every 3 to 4 batches, and change it completely every 20 or so batches.  Changing the oil takes about 2 minutes, and you don’t need any special tools to get it done.  Specialty vacuum pump oil costs about $10 to $12 per fill, so if you run 10 batches a month, the oil will cost you about $60 to $80 per year.
• Oil-Free Pump – The oil-free pump is an upgrade from the “premium” pump, costing an extra $1500.  That’s quite a bit, but you won’t have the ongoing cost of oil, or the extra maintenance.  This is a good option if you have extra cash to spend and are looking for something more self-maintaining.  While you don’t have to deal with oil, this pump uses a bit more electricity to run and is a bit louder to operate.

They used to have a “regular” oil pump that needed an oil change every 3-4 batches, but the premium pump replaced that one.  You can still sometimes see those for sale secondhand, or you can purchase replacements of this old-style pump from Harvest Right for about half as much as the premium pump (or 1/5th as much as the oil-free).  They don’t ship new freeze dryers with this pump anymore.

I have the “premium” pump rather than the oil-free, mainly because I’ve read everywhere that they’re more dependable and longer lasting than the oil-free version.

The box of freeze dryer accessories included with my home freeze dryer, including the premium vacuum pump.

I was pretty intimidated by changing the oil in the pump, but it’s incredibly simple.  You literally put a container under the pump, then turn a knob a quarter turn and let the oil out.  Close the knob, and pour new oil into the top.

From start to finish, it took about 2 minutes.  Really, it’s nothing to worry about, even if you don’t consider yourself mechanically inclined.

Changing Vacuum Pump Oil in a Harvest Right Freeze Dryer. Simply turn the knob, let the old oil out, and then add new oil at the top.

Pharmaceutical and Scientific Freeze Dryers

They also make pharmaceutical freeze dryers, which are designed to work with things with low moisture content.  You cannot use those for freeze-drying food, and they’re mostly just used for pharmaceutical “plant material” that’s become available in certain states recently.

Lastly, they have scientific-grade freeze dryers, allowing you to precisely set just about anything on the machine to match what’s needed for laboratory conditions.  Unless you’re a scientist who needs to mimic moon conditions, they’re not a good idea.  You’re better off with home scale models with the right pre-sets for freeze-drying food at home.

Freeze Dryer Location and Setup

A freeze dryer consists of two parts, a freeze-drying chamber, and a vacuum pump.

The freeze dryer itself is pretty hefty and weighs around 60 to 140 pounds (depending on the model).  The medium model is 19 inches wide by 25 inches deep and 29 inches high.  (For reference, the average kitchen countertop is about 36 inches tall and 25 inches deep.)

The pump is smaller and weighs about 30 lbs.  It can sit beside or on top of the freeze-dryer.

Since the freeze dryer needs to drain after each cycle, it cannot be placed directly on the ground.  It needs to be raised up at least 6”, but it can be placed on a sturdy kitchen countertop that’s built to hold the weight. 

We have our freeze dryer in the garage, and it’s just set up on top of the pallet it came on.  Someday I hope to have a preservation kitchen large enough to set it up on a counter, but it works great in the garage for now.

When choosing a location, keep these things in mind:

Noise

The vacuum pump is reasonably loud, roughly as loud as a household vacuum cleaner.  The machine runs for 16 to 36 hours at a time, so it will be running overnight while you’re trying to sleep.  Most people wouldn’t want this to be anywhere near their bedroom. 

Electric Requirements

Small and Medium-sized freeze dryers work on a standard household outlet, but they recommend a dedicated 20 amp circuit. 

Large and Extra Large Models still use regular 110 electricity, but they need a specialty NEMA 5-20 plug, and a dedicated 20 amp circuit is required.  The special outlet is easy to install, and an electrician can put it in on any existing dedicated 20-amp circuit in a matter of minutes.  (We actually did ours ourselves, as that’s legal in VT, but check your local code requirements.)

Temperature

The compressor and pump have trouble working at very high or very low temperatures. 

Ideally, the freeze dryer would be placed somewhere between 45 and 80 F when running.  This is especially important if you’re keeping a freeze dryer in a location that’s not climate controlled and you live in a very hot or very cold climate. 

If it’s hotter than 75 to 80 degrees, the vacuum pump may struggle, and cycles will take longer.  Harvest Right recommends buying a household fan to set up nearby in very hot locations to help cool things down.

Weight

Be sure that wherever you place it can hold the weight, and that it’s sturdily built and anchored.  Small kitchen carts could tip over if they had this top-heavy machine on them, so be sure you’ve thought out where to put it before ordering it. 

For us, a pallet in the garage works great.  It’s right under our electrical panel, so it was easy to wire in a dedicated circuit for it.  The pallet is sturdy enough to hold it, and high enough for it to drain, so it gets the job done.

Garages also tend to work well because they’re an easy place for the delivery truck to access.  The delivery truck will drop it with a lift gate, and then use a pallet jack to move the freeze dryer into position. 

That’s incredibly convenient if you have a garage on a cement slab, so you never really have to physically move the heavy appliance by hand. 

(Still, my husband and I are healthy adults, and we can lift and move the freeze dryer if needed.  If and when it ends up on a kitchen counter, we’ll move it there ourselves without too much trouble.)

Our freeze dryer, is on the pallet exactly as it was delivered (minus the exterior box and padding). Before use, we removed the foam padding underneath and turned it around so it had its backside toward the wall. Other than that, it’s exactly how it came

Preparing Food for Freeze Drying

Most foods can be placed directly onto the freeze dryer trays in whatever form is most convenient for later use.

The food may be either raw or cooked, depending on how you’ll use it later.

For example, frozen raw eggs can be rehydrated and used instead of fresh eggs in baked goods, or simply cooked like scrambled eggs.  On the other hand, freeze-dried cooked eggs are already cooked, and they make a quick and easy just add boiling water camping meal.

The same goes for meats, which can be put up either raw or cooked.

Fruits and vegetables should be washed and sliced into pieces that are all about the same size to help them freeze dry evenly.  Slice produce with skins, like apples and plums, and place them cut side up on the trays so moisture can escape during freeze-drying.

Be aware that freeze-drying does not sterilize food or kill bacteria.  It just basically stops time in terms of spoilage by removing water so that enzymes and bacteria cannot multiply. 

Once you rehydrate the food, it still has all the same bacteria on it that it did when it went into the machine.  Be sure your food is clean and fresh when it goes into the machine, and refrigerate it once you’ve rehydrated it if you don’t intend to consume it immediately.

It helps to pre-freeze food on the trays before freeze-drying, but that’s not strictly required. 

When you’re working with something that’s liquid, like milk, eggs, or soup, the manual suggests inserting the empty tray 3/4 of the way into the freeze dryer and then pouring the liquid into the tray.  This helps prevent tipping and keeps the food from spilling. 

Obviously, you cannot pre-freeze the food in that case, but that’s for the best, as liquids would likely tip/spill from the trays in the freezer anyway.