Learning how to preserve food is a skill that will have your future self thanking you for years to come! Keep reading to learn how to freeze dry food for long term storage!
I'll break down the science behind freeze drying, chat about how it works, and then give you some practical advice on how you can do it at home. Plus, I'll tackle some of the most burning freeze-drying FAQs that might be simmering in your mind.
- What is freeze drying?
- What is the difference between freeze-dried and dehydrated food?
- How long does it take to freeze-dry food in a freeze dryer?
- What are the advantages of freeze-drying?
- What are the disadvantages of freeze-drying?
- How long do freeze-dried foods last?
- What is the best way to store freeze-dried foods?
- An example: how to store freeze dried eggs
- Are there foods that should NOT be freeze dried?
- Here are the wildest foods we have freeze dried (and whether we liked them or not!)
- How to use a freeze dryer
- That's a wrap!
Just a heads up, I want to be transparent that this post was made possible by the incredible team at Harvest Right. They provided me with a freeze dryer last spring and I have been using it almost non-stop ever since!
As an amazon associate, this post contains affiliate links, which means I make a small commission at no extra cost to you. See my full disclosure here.
What is freeze drying?
Freeze-drying, a relatively recent method of home food preservation using a home freeze-dryer, has been gaining attention recently. While commercially freeze-dried food has been around for years, the past decade has witnessed an upsurge in the popularity of home freeze dryers.
So, what's the deal with freeze drying? It's a twofold process that works wonders on preserving food. First up, the food gets frozen as it's plunged into subzero temperatures (around -40°F). This chilly phase causes the water content within the food to transform into vapor.
Once the water vapor is released, the pump kicks on and starts vacuuming up the vapor. This vacuum process is much like a food dehydrator, only way more powerful. It's a dual effort – vapor gone, moisture gone. This is called sublimation.
What is sublimation?
Sublimation is the transformation that takes place during freeze drying. When food is frozen to extremely low temperatures, the water within it changes from a solid (ice) directly into vapor without passing through the liquid phase. This process, known as sublimation, removes the water content from the food while preserving its structure, nutrients, and flavors. It's like a disappearing act that leaves behind all the good stuff!
What is the difference between freeze-dried and dehydrated food?
Now, here's the kicker: freeze-dried food stands apart from its dehydrated counterpart. It's like comparing apples and oranges, or in this case, freeze-drying and dehydrating. They're different, no doubt, but here's the scoop – different isn't always a synonym for better!
In the picture above, the tomatoes on the left are dehydrated and the tomatoes on the right were freeze dried. They looked exactly the same before preserving, but the dehydrated tomatoes have a vivid red color and are tiny and wrinkled. The freeze dried tomatoes are more pale and look exactly like a slice of tomato, only very lightweight.
With dehydrating, the food does is not frozen and therefor no water vapor is released. There is also no vacuum to really effectively slurp out all of the moisture from the food. Dehydration is simply drying, usually with air circulation.
Dehydrating is one of my very favorite methods of food preservation. If you've been on my instagram page for very long, you've surely watched me dehydrating deer jerky, pepper flakes, fruit leather, tomato skins, okra or other fresh foods. For a deeper dive into dehydrating foods, read my post How to Use a Food Dehydrator.
How long does it take to freeze-dry food in a freeze dryer?
Alright, let's talk time. Freeze drying isn't an overnight affair – it's more like a slow dance. The exact time depends on what you're freeze-drying and how much of it you've got. Generally, we're talking about 24 to 48 hours. Yep, it's a bit of a wait, but trust me, the end result is totally worth it. Just think about all those future delicious meals you'll be having.
The ice cream sandwiches in the picture below took 32 hours to freeze dry.
What are the advantages of freeze-drying?
Freeze drying is super easy and user-friendly. But beyond that, there are so many cool benefits! Here's a short list of the best benefits:
1. Nutritional value: Freeze drying retains a higher percentage of nutrients compared to other preservation methods. The low temperatures involved in the process help minimize nutrient loss, making freeze-dried foods a more nutritious option.
2. Intense Flavor: Freeze-dried foods tend to maintain their original flavors remarkably well. Since the process involves minimal heat exposure, the natural taste of the food is preserved.
3. Long-term storage: One of the crowning glories of freeze-drying is its impressive shelf life. Freeze-dried foods can last for an incredibly long time – often several years – without the need for preservatives. This is due to the removal of water, which inhibits microbial growth.
4. Lightweight and Compact: Freeze-dried foods shed their water weight, resulting in a lightweight and compact final product. This makes them a fantastic choice for outdoor enthusiasts, backpackers, and emergency food supplies, as they're easy to transport and store.
5. Minimal Loss of Appearance: Freeze-dried foods tend to maintain their original shape and appearance quite well. Whether it's a strawberry, a chunk of meat, or a sprig of herbs, freeze drying ensures that your food looks as appealing as it did before.
6. Rehydration Magic: A little water is all it takes to bring freeze-dried foods back to life. They rehydrate quickly and often retain much of their original texture, making them convenient for on-the-go meals or quick cooking.
7. Reduced Bulk: Freeze-dried foods take up significantly less space compared to their fresh or dehydrated counterparts. This can be a game-changer when it comes to storage, especially for those with limited space. There are many foods, like tomatoes, milk or eggs that can be ground into powder after freeze drying, which condenses the food into a very small pantry footprint! The herbs below were ground into a fine powder and take up very little space!
What are the disadvantages of freeze-drying?
Now, while freeze-drying is pretty darn amazing, like all things in life, it's got a few quirks. First off, freeze dryers can be a bit on the pricey side. So, if you're thinking of jumping into this world, be prepared to invest a bit upfront.
Also, freeze-drying isn't a magic wand that works for everything. Some foods might not turn out as you'd expect, so it's a bit of trial and error. And remember, freeze-drying doesn't give you superpowers – your food will still need proper storage to stay at its best.
Foods that have high water content, are fatty or have a dense skin will not freeze dry as well.
Lastly, freeze-dried food can sometimes lack that "fresh off the stove" texture. It's not a deal-breaker, but some foods might be a bit different in texture after the process.
How long do freeze-dried foods last?
Freeze-dried foods are known for their impressive shelf life, often extending far beyond what is achievable with traditional preservation methods. The longevity of freeze-dried foods can vary based on factors such as storage conditions, packaging, and the specific food item.Here's a general guideline for long term food storage of common freeze-dried foods:
- Berries (strawberries, blueberries, raspberries): 15-25 years
- Apples: 20-30 years
- Bananas: 15-25 years
- Peas: 25-30 years
- Corn: 20-30 years
- Carrots: 20-30 years
- Beef: 15-25 years
- Chicken: 15-25 years
- Turkey: 15-25 years
- Milk: 20-25 years
- Cheese: 15-20 years
- Yogurt: 15-20 years
5. Pasta and Grains:
- Rice: 25-30 years
- Pasta: 20-30 years
- Oats: 15-25 years
- Trail Mix: 20-25 years
- Potato Chips: 15-20 years
- Nuts: 15-25 years
It's important to note that these estimates are approximate and can vary based on individual products and packaging. Storing freeze dried foods in plastic bags or a simple airtight container will not be as good as using smaller mylar bags. Proper storage conditions, such as keeping freeze-dried foods in a cool, dry, and dark place, can help extend their shelf life.
Additionally, some freeze-dried foods may still be safe to consume beyond the recommended shelf life, although their quality and taste may gradually decline over time.
What is the best way to store freeze-dried foods?
When storing freeze-dried foods, consider using vacuum-sealed packaging, Mylar bags, or airtight containers to help maintain their freshness. Regularly inspect your stored items and rotate them to ensure you consume the oldest products first and maintain a well-stocked supply of delicious and nutritious freeze-dried treats.
My method for storing freeze dried foods is to use repurposed spice or mason jars for freeze dried foods that are in my working pantry. This is for foods I am using regularly, like freeze dried diced garlic or powdered onions.
General guidelines in my kitchen are that fresh food that is freeze dried will be good for long periods with an airtight seal on a mason jar, mylar bag or vacuum storage bag. For best results, look at the food and check for signs of physical change or too much oxygen.
For foods that I am planning on keeping for 1-2 years, I use sealed mason jars. I have a jar sealer that can be used to remove the air from jars and actually seal the jar, almost as if it had been run through a canner.
When I am preserving a food that I don't plan on eating for a very long time, or I am using to prepare for a possible emergency food shortage, I like to use mylar bags with oxygen absorbers. I buy my mylar bags, impulse sealer and oxygen absorbers directly from Harvest Right. I have also used Wallaby and had good results.
An example: how to store freeze dried eggs
The freeze dried eggs in the photo below are ground into powder and stored in mason jars. We took them on a float trip for easy just-add-water scrambled eggs! We cooked them over the fire and they turned out perfect! For long term storage, I put the extras in mylar bags with oxygen absorbers.
Are there foods that should NOT be freeze dried?
While freeze-drying is a versatile food preservation method, there are some types of foods that may not be suitable for the process due to their composition, texture, or other factors. Here's a list of foods that are generally not recommended for freeze-drying:
1. High-Fat Foods: Foods with a high fat content, such as fatty meats or oily fish, may not freeze dry well. The fats can become rancid during the process, affecting the quality and taste of the final product.
2. Dairy Products with High Fat Content: Creamy dairy products like heavy cream, full-fat yogurt, or rich custards may not yield satisfactory results due to their fat content. I have successfully freeze dried whole milk, skim milk and colostrum.
3. Whole Eggs: Freeze-drying whole eggs is not recommended. The best way to freeze dry eggs is to crack them into a bowl and whisk until the yolks and whites are well blended. Then pour them into the trays and pre-freeze before freeze drying. My medium Harvest Right with 4 trays can freeze dry 72 eggs in about 36 hours.
4. Foods with Alcohol: Foods that contain alcohol, like alcoholic beverages or certain sauces, may not freeze dry well, as alcohol can impact the freeze-drying process and result in undesirable flavors.
Here are the wildest foods we have freeze dried (and whether we liked them or not!)
I think if you asked my husband and kids what their favorite freeze-dried food is, they would all say fruits like strawberries, pineapple and raspberries. The fruits become light and airy, and basically melt in your mouth!
One of the most unexpectedly odd foods I have freeze dried were avocados. I bought a dozen avocados during a sale and cut them into ¼ inch slices and placed then in a single layer on the trays.
When the avocados were done, they looked exactly like they did originally, but the texture was wild! Biting into a freeze dried avocado was just like biting into a cashew. Kind of hollow, but also had a bit of bite to it. I used them as toppings for salads and even rehydrated some for homemade freeze dried mango & avocado salad!
How to use a freeze dryer
1: Gather Your Supplies
Ensure you have all the necessary equipment and ingredients ready: a freeze dryer like my Harvest Right, food items to be freeze-dried, mylar or vacuum-sealed bags or containers, oxygen absorbers (optional), and any additional tools required for food preparation.
2: Prep the Food
- Wash, peel, and slice the food items as needed. Blanching certain fruits and vegetables before freezing may help preserve color and texture.
- For cooked dishes, prepare and cook the meals according to your recipe. Avoid over-seasoning, as flavors can intensify during freeze drying.
- Foods like meat and eggs can be freeze dried raw and cooked after rehydrating.
3: Load the Freeze Dryer Trays
- Arrange the prepared food items evenly on the trays, leaving some space between them to allow for proper air circulation during the freeze-drying process. If possible, pre-freeze your foods on the trays overnight in a deep freeze.
4: Set the Freeze Dryer Parameters
- Consult your freeze dryer's user manual for specific guidelines on temperature and time settings. Generally, you'll want to start with a low temperature and gradually increase it as the process progresses. My machine doesn't need to be set, it will sense how much time the food needs and adjust as needed.
5: Initiate Freezing
- Start the freeze-drying cycle. The freeze dryer will gradually lower the temperature to freeze the food items. This stage helps preserve the food's structure and prevents ice crystals from forming.
6: Begin Vacuum and Sublimation
- After freezing, the vacuum pump will kick in to create a low-pressure environment within the freeze dryer.
7: Monitor the Process
- Keep an eye on the freeze-drying process. Depending on the type and quantity of food, the duration can vary from hours to days.
8: Test for Dryness
- To determine if the food is adequately freeze-dried, remove a sample piece and break it in half. It should be dry and brittle, with no visible moisture.
That's a wrap!
And there you have it! From nutrient preservation to an extended shelf life that would make any pantry proud, freeze drying has truly earned its place as a very handy method of food preservation.
The freeze dried sourdough starter in the picture above is a perfect example of how food retains it's nutrients and capabilities. It's freeze dried now, but if I just add water it will perk back up and I can use it for baking a loaf of sourdough bread!
But here's the best part – it's not just for the pros. You, yes you, can start freeze drying right in your own kitchen. The process might sound a tad scientific, but it really isn't. Once you've got the hang of it, you'll wonder how you ever lived without freeze-drying.
Remember, the journey of freeze drying is a learning experience – a bit of trial, a sprinkle of error, and a whole lot of deliciousness. So go ahead, give it a whirl, and don't be surprised if you find yourself freeze drying everything you can get your hands on (we aren't going to talk about all of the mark down bananas I have in jars in my basement)!