Answer: About 16 – 40 hours, depending on several Factors.

When you imagine the process of food preservation, traditional methods like canning, pickling, freezing, or dehydrating might be the first things that pop into your mind. However, new technologies have provided a better option: Freeze Drying. This option is superior to the traditional methods by far for the long-term preservation of food. But how long does freeze-drying food take with a home freeze-dryer?

Woman looking at watch to see how long does freeze drying food take.
How long does freeze-drying food take?

The Freeze Drying Process Explained (reading ain’t my thing version) in a tiny basic nutshell.

  1. Freezing
  2. Creating Vacuum
  3. Change Ice to Gas – skipping liquid state
  4. Final Drying – By raising the temperature

Ok, Back to those “Several Factors.”

  • Machine Quality
  • Vacuum Pump Efficiency
  • Food Type
  • Food Thickness
  • Pre-frozen or fresh
  • Displacement of food on the tray
  • Room Ambient Temperture
  • Room Humidity

Freeze Drying Process Explained (I’m intrigued; tell me more version)

Step 1: Freezing

Upon placing the food in the freeze dryer, it’s rapidly frozen to temperatures as low as -40F.

Step 2: Creating Vacuum

Next, a vacuum pump removes air and creates a near-zero pressure environment inside the chamber.

Step 3: Sublimation

The food warms up (+50F), encouraging the frozen water to sublimate directly from solid ice to a gaseous state, bypassing the liquid phase.

Step 4: Final Drying (Secondary Drying)

Lastly, the temperature is raised to (+68F) to remove the remaining moisture, making the food completely dry. 

So, How Long Does Freeze Drying Food Take?

Here’s where it gets interesting. The duration of the freeze-drying process at home hugely depends on several factors:

Machine size and efficiency

Compact home freeze dryers processing around 7 – 10 lbs. of peaches can take around 24 hours (according to a Utah State University study), while Blue Alpine runs about 15 lbs. of fruit in about 18 hours.

  • Machine’s functional capacity (pump size to chamber size to food moisture level.)
  • The efficiency of the vacuum pump (oil or oil-less, how high is the CFM’s-how long it takes to move 1 Cubic Foot air flow can be moved in one Minute.)
  • The overall quality of the machine (seals, connections, the “Smart Technology” sensors, etc.)

Type and thickness of food

Different foods freeze dry at different times, and the thickness plays a significant role.

  • Meats, vegetables, and fruits all have different water content and density, affecting the time taken. To go along with that, kiwi would naturally take longer than, say, bananas.
  • Thick pieces take longer to freeze dry than thin slices.
  • Fresh vs. Pre-Frozen (Fresh takes longer)
  • The density of the food item plays a factor also. Denser = more time compared to a food item of the same moisture content but less dense.

Room conditions

Surprisingly, the room that your freeze dryer is in can affect how long the process takes.

  • Ambient temperature
  • Humidity level
  • You locations Elevation

The answer to “How long does freeze-drying food take?” isn’t just Cut and Dry.

(See what I did there, just Cut and Dry, BAHAHAHAHA)

Seriously though, considering all these factors, a regular cycle in a home freeze dryer typically takes between 20 to 40 hours. Yes, that sounds like a long time, and it is! But set it and Forget it! (but make sure you check on it randomly) The results are well worth the wait; when you consider buying store-bought freeze-dried food, it costs about 85% more than doing it yourself.

The Time Factor: Preserving Nature’s Bounty

The benefits of freeze-drying food at home are significant. However, the run time may be lengthy.

  • Extends shelf life: Freeze-dried foods can last for years, making it a sustainable form of preserving seasonal produce. (25 to 30 years)
  • Retains nutritional value: This method of food preservation keeps 97% of the nutritional content.
  • Hassle-free storage: Lightweight, portable, and compact, freeze-dried food takes up little storage space.
  • Easy rehydration: Freeze-dried food easily rehydrates with a splash of water—perfect for Instant meals. (A splash of water isn’t necessarily true. It once again depends on the food. Naturally high moisture foods need more moisture to rehydrate)

Pro Tips for the Shortest and Most Efficient Drying Cycle.

How long does freeze-drying food take? That depends on you. The key to shorter and more efficient drying cycles is in preparing your food to be dried. 

Blue Alpine explaining the importance of pre-freezing food.
  • Pre-freeze the food before putting it into the freeze dryer. 
  • Choose the same food or foods with the same water content so the entire batch dries at the same rate.
  • Use a mandolin or other equipment to get uniform thickness and consistent slices.
  • Maintain uniform spacing between food on the tray.
  • Make sure the Vacuum Pump Oil is clean before each use.
Blue Alpine explaining changing freeze dryer vacuum pump oil

FAQ’s

Why does freeze-drying take so long?

Freeze-drying involves removing water from a substance by freezing it and then subjecting it to a low vacuum and increased heat, which allows the frozen water to change directly from a solid to a gas without passing through a liquid phase. This process requires time for the water to sublimate, or evaporate, completely.

What is the duration of freeze-drying?

The duration of freeze-drying varies depending on the specific product and its characteristics.

How can I speed up my freeze-drying?

To speed up freeze-drying, you can try the following:

Pre-freeze the product.
Adjust your freeze-dryer program settings.
Use thinner and uniform-sized pieces.
Do not overload trays. Keep items spaced evenly, just like baking.
Optimize the vacuum level to enhance drying efficiency.

Please note that any modifications should be done carefully to ensure product quality and safety.

What foods Cannot be freeze-dried?

Foods with high-fat/high oil content, such as nut butter or a solid chocolate bar. These items will not freeze-dried effectively.

How should I store my freeze-dried food?

Store freeze-dried food in a cool, dry place with a temperature range of 50-70°F (10-21°C). Ensure it is sealed in airtight containers, such as cans, Mylar bags, or vacuum-sealed pouches. Keep it away from moisture, light, and heat sources to maintain its quality and extend its shelf life.

How much food can you freeze dry at a time?

The amount of food you can freeze dry at a time depends on the capacity of your freeze dryer. It’s best to refer to the manufacturer’s guidelines or specifications for the specific model you are using.

In Conclusion: A Time Worth Investing

Even though the freezing drying cycle time can take a while, the time required of you is minimal. Once complete, your food will (once rehydrated) retain its taste, texture, and 97% of its nutritional value. You can only achieve that one way: Freeze Drying, not to mention after sitting on a shelf for 25 to 30 years (if stored properly). The minimal amount of time you’ll invest will give you a return of peace of mind when you can enjoy healthy, quality foods you’ve created without sacrificing nutrition, taste, texture, or health. So, stop watching the clock and start your freeze-drying journey today! The hands of time wait for no one!

“If you enjoy what you do, it’s not a waste of time. Life is too short; do what you enjoy.” 

Image by: Image by cookie_studio on Freepik