When I began posting in my stories on Instagram about using a freeze dryer, I got a lot of questions. The most frequent question was, “What is the difference between freeze drying and dehydrating?”
In this article I’ll answer that question, and also give you a few freeze drying tips for beginners to help you get started with freeze drying.
Disclaimer: This post may contain affiliate links. See my disclosure policy for more information.
What is the difference between freeze drying and dehydrating?
First, a basic overview of both processes:
Dehydrating is a centuries-old method for preserving food. Drying meat, fish, and plants in the sun was a simple way to preserve food before electricity.
Modern dehydrators use a form of energy (usually heat carried by hot air) to reduce the moisture level in foods, which then increases the storage life of the food.
Because of the heat, about half of the nutritional value is lost, and the texture, taste, and appearance changes.
On the other hand, freeze drying is a relatively new form of food preservation and was invented in 1906. Freeze drying is a much more complex process that requires specialized equipment.
The food is cooled to a very low temperature of at least -40°F (-40°C) until frozen. A vacuum is formed around the food, and the slowly-rising temperature turns the water in the food from a solid to a gas without passing through the liquid state.
Freeze drying doesn’t shrink the food or toughen it. Most of the nutritional value remains.
Why choose freeze drying?
That’s the technical side of it — but what all that means is that freeze dried food retains more of the flavor and nutrients than dehydrated food. Freeze dried food typically rehydrates more easily, and will more closely resemble the original flavor and texture of the food.
When I got my freeze dryer, I was surprised at how simple the process was. You really do just push a few buttons.
The sensors inside the machine monitor the temperature and internal moisture levels of the food. At the end of the processing, you double check that it is done or if it needs more drying time.
I’m so excited to have this new way (for me) to preserve abundant garden harvests. I’ve already freeze dried bell peppers, hot peppers, roselle, lemons, cilantro and green onions from the garden. I’m looking forward to freeze drying even more garden harvests too.
Freeze Drying Tips for Beginners
- Pick a good location for your freeze dryer. The machine will run for 24-48 hours and can be loud at times. Do not store it someplace hot. The machine heats up while using, and if it gets too hot it will not operate properly. I keep my freeze dryer in the laundry room. I have the medium freeze dryer with the premier pump from Harvest Right.
- Have a sturdy cart to place the freeze dryer on. The cart needs to be able to hold at least 250 pounds. This is the cart I use.
- Watch the set-up videos on Harvest Right’s website, and read through the instruction manuals that come with the freeze dryer.
4. Don’t overload your freeze dryer. Freeze dry small, similar-sized pieces. Freeze dry similar (or the same) ingredients on each shelf. Different ingredients may have different drying times.
5. Start with something simple like herbs. Herbs are simple to prepare for the freeze dryer and they freeze dry quickly.
6. Choose the best way for you to store your freeze dried items. Because I’m not using mine for long term storage, and will be opening and closing the jars often, I’m storing in half gallon glass canning jars with a leak proof lid (without an oxygen absorber). For longer storage (up to 25 years!), use mylar bags and oxygen absorbers.
Learn more about how to make and use freeze-dried celery in this article.
Don’t have a freeze dryer?
Purchasing a freeze dryer is undoubtedly an investment. My freeze dryer runs almost nonstop, and I’m grateful to have one. I have the medium-size freeze dryer with the premier pump from Harvest Right.
If you are purchasing a freeze dryer, please consider purchasing through my affiliate link. (It doesn’t cost you more, and I earn a small commission.) Your support helps me continue providing free content here on my blog and YouTube channel.
Friday 14th of April 2023
Thanks for all of the information, Angela. I learned a lot. I guess I'll stay with dehydrating for now. The freeze drying machine is a little pricey for me.
Betty Jo Quigley
Tuesday 2nd of August 2022
How do you keep a record of what you are freeze drying and what info do you record? Do you weigh every pan? Is it important to record how long it took to dry? Any thing else?
Wednesday 3rd of August 2022
It depends on how detailed you want to be with your records. Keep track of whatever information you feel is important to record and remember.
Wednesday 29th of June 2022
Does the freeze dry machine require a special electrical outlet or certain wattage?
Saturday 15th of October 2022
@Lu, it depends on which one you get. The small and medium models don’t. The large one requires a dedicated 20 amp circuit and a 5/20 plug.
Sunday 2nd of October 2022
@Lu, The large Harvest Right Freeze Dryer does require a Dedicated 20 Amp Circuit. The Small and Medium can use an existing 15 Amp Circuit, but I would not put it on a circuit that has other appliance’s on it.
Thursday 30th of June 2022
Check with Harvest Right to see the specific requirements.
Monday 14th of March 2022
How long do you feel the items in the glass jars will last as opposed to the myler bags with oxygen absorbers?
Tuesday 15th of March 2022
From what I've read, about a year or more. I'm using jars for my short-term storage and using mylar bags for longer term storage.