FOOD & COOKING

How to Freeze Dry Food: Literally the Coolest Thing Ever

How to Freeze Dry Food
Russell McCarty
Written by Russell McCarty

Don’t you just hate thawing frozen food? It tastes pretty awkward, and its texture isn’t a point in its favor either. Besides, how would you carry 10 pounds of frozen meat and vegetables if you were going backpacking? Or in an emergency? It would be the fabric of nightmares. But we have a solution: learn how to freeze dry food.

Yes, there is such a thing. Among its many benefits we’ll discuss below, the food weighs much less, and it’s incredibly compact for increased portability. Not to mention it can last for years. And the freezing process isn’t complicated either, you’ll just need the right tools.

Frozen Raspberries

So if you want to learn more about this fascinating topic, read on. In this article, we’ll discuss some general information relating to the whole process, so you can understand how and why it works. After that, we’ll talk a bit about the freezing and de-freezing process, so you can customize these depending on your food items, the time you have, and your main purpose.

The Process

There are many interesting things to know about freeze drying your food, but this is not a new concept. The truth is that it’s as old as the mid-20th century since it was first used in the Second World War when supplies were scarce and soldiers needed good food but couldn’t afford to bring a refrigerator to the battlefield. And even though it all started with beverages such as coffee, today’s world sees a lot of food being preserved this way, from vegetables to dairy, to meat and spices.

So How Does It Work?

Well, it’s pretty simple, though the name is as complicated as the pronunciation of two Greek words combined for a non-speaker. But basically, this word means the love for dissolving, which is exactly what freeze drying does. So after you lower the temperature to make sure your food froze, you apply a vacuuming process at a huge pressure to make sure the water molecules are sucked out of the food.

Freeze Dried

The water dissolves itself from the food molecules in the form of a vapor because the pressure is very high for the hydrogen-oxygen combination of atoms. That way, the food remains dry, while the water gets to a condenser where it’s transformed into ice and out of the picture.

With that, you would probably think the process is complete, but unfortunately not all water molecules can be sucked out of your food with the vacuum. Instead, you need to get what remains through a heating process, which transforms water into gas. Besides, this heating helps the food keep its molecular structure, so it’s good and ready for you to eat it, helping you reintroduce moisture for de-freezing it later on.

What Are the Advantages?

So, why choose this method? What can it bring on the table? If you’re out camping, why not bring along a portable refrigerator? Or if you’re at home, why not use your own refrigerator?

Refrigerator for Freezing

These are all valid questions which we’ll answer below.

It tastes better

Let’s start with this: if you’ve ever thawed a food item, how did it taste? Was it as good as when it was fresh? Chances are the answer is no because traditional freezing changes the physical structure of things since it adds water molecules to the process. But with freeze-drying, you’re keeping the same molecular structure of your food, which means it will taste as good as before and have the same texture.

But it’s not all about the texture and taste here. With freeze dried food, you can have the same nutrients and vitamins too, although we have to admit the levels of vitamin C and E are lower. So make sure you compensate this loss with some fresh fruits and veggies if you’re using dry freezing for the long term.

It’s an asset for your survival backpack

While the traditional method of freezing keeps food good enough for a few months, this innovative process makes it good enough for years. Don’t just take our word for it either, this thing’s been tested by different food companies, as well as lots of people.

Since freeze dried food can last for years, it’s great to freeze some for that specific purpose too.  As we live in a world filled with uncertainties ranging from economic crises to wars, apart from all the earthquakes, tsunamis and power outages, it’s wise to have some provisions.

And we can do better than canned food when it comes to more nutrients, minerals, and vitamins, as well as taste, right? Besides, water constitutes a large part of your food items, between 60% to 90%, so with that gone, you can have more space in your emergency backpack for other stuff.

It’s great for camping

If you’re hiking, backpacking or camping, it can be a real nuisance to bring your own mini-refrigerator or, even if it’s small and light. But you still need to protect it from impacts, you might still need ice for some models, and let’s be honest – every pound counts.

Besides, with all the water removed through the lyophilization process, the food will weigh much less, which is a definite advantage for portability.

Freeze Dried Food for Camping

Image credit: offgridweb.com

Now, that’s amazing because you can eat better and more nutritious food for lots more energy when you’re camping, not to mention you can prolong your trip.

What Can You Store?

With that into account, you might be ready to proceed with your freeze drying. But what can you use it for?

  • Beverages
  • Fruit
  • Vegetables
  • Meat and eggs
  • Seafood
  • All dairy products
  • Instant foods
  • Pasta
  • Fruit extracts
  • Ice cream
  • Herbs and spices
  • Baby formula

But not all these foods can be stored equally well, you know, especially bigger ones. That can easily be solved though, through a very complex process known as “temaxismo” or in layman terms “cutting and slicing”.

Since bigger chunks of food have more water molecules, the vacuuming and the heating processes can leave a fairly big amount of water inside them. Freeze drying gets rid of 98% of the water, but 2% of a lot is still a lot.

Freeze Drying Food

Image credit: yourdiningcenter.com

Besides, don’t forget to cook all your meat and seafood before the actual freezing. You can also apply this process to other things apart from food, like flowers, medicine and even important documents, which is a bit different, though.

How do You Actually Do It?

So, we’ve finally arrived at the interesting stuff. Now you know the basic principles of freeze drying, so you can get to it. There are a few different methods for this, but it all starts with the:

The Preparation Stage

This stage consists of two main steps: planning and processing, so let’s start:

Planning

We did say above that all food items can be used for dry freezing, but they’re not all as good. You should pick particular items depending on your purposes, like more high-calorie for backpacking or more nutrient-dense for survival purposes.

Cucumbers and Peppers

However, you should still take into account that:

  • If there’s more water into a certain food item, it will freeze better. That means you should choose fruit like berries, apples, and pears or vegetables like cucumbers, peppers and potatoes.
  • Once you have successfully frozen vegetables and fruit with a high water content, you can move on to meat, cheese, and actual meals.
  • You should choose very fresh and ripe fruits and vegetables because these are the ones that will taste better when you reconstitute them.
  • Once you cook the meat, wait for it to cool down, then freeze it on the same day.
  • When it comes to freezing whole meals, don’t freeze your leftovers, particularly if they’ve been sitting in the fridge for some time, because they’ll taste horrible. Or at least, not that good.
  • It’s not a good idea to freeze food items that taste bad when you reconstitute them. For instance, products made with yeast like bread and cakes are really depending on their fresh texture, and have less water.

Processing

During this step, you need to make sure that the food items are good to freeze, so you need to:

  • Wash and dry your fruits and veggies.
  • Cook the meals.
  • Cut and slice your food into smaller portions.

The Freezing Stage

We’ve already talked a bit about freezing food with a vacuum, but the truth is that you can use different methods if you can’t afford this one.

Cutted Vegetables

We’ll review each of them below, so you can compare the pros and cons easier.

  1. The Freezer Method

After you’ve prepared all the food items and meals, follow these steps:

  1. Put all the food on a bigger plate or on a tray, making sure the slices have enough space between them.
  2. Use a deep freezer and set it at the lowest temperature.
  3. Remove everything you have from your freezer, and put this plate inside it.
  4. Keep the freezer door closed until your food items have all frozen.
  5. Don’t take the food out at all while the food is freezing, it should take about a week for sublimation to occur so that water gets removed from your food.
  6. After a week, take a piece of food out of the tray and let it thaw. If it doesn’t turn black, it means you’ve succeeded.
  7. Now, it’s time for storing your food, so put it in storage bags, making sure these are airtight.
  8. You can place these bags back in your freezer, or in your pantry. You can even put them in an emergency backpack, but that should be kept in a cool, dry place too.

PROS:

  • Everyone has a freezer and a plate
  • You don’t have any additional costs for new gadgets
 CONS:

  • Your freezer must be completely empty
  • It takes a long time
  • It doesn’t dry the water out completely
  • You can’t use it for a lot of food at once

At this point, you might be wondering how all this is different from the traditional freezing method.

Emptying the Freezer

It seems like we’ve just described traditional freezing but named it dry freezing, right? Well, not quite. Although this isn’t as performing as actual vacuum dry freezing, it’s different than regular freezing thanks to the sublimation process.

So the basic differences are that:

  • The food is cut into small bits and slices.
  • The freezer is completely empty.
  • You’re not constantly opening the freezer to add or get food.

Thanks to that, you’re basically creating a rudimentary sort of vacuum around the water molecules. And water behaves very interestingly in a vacuum, meaning it can never reach a liquid state.

How to Freeze Dry Food: Literally the Coolest Thing Ever

Image credit: gumtree.com

Therefore, once you take the food out of the freezer, thanks to this quirk, the water will immediately transform into a gas and evaporate instead of becoming liquid. This is what sublimation actually is, and we’ll see it at play in the Vacuum Method below too.

  1. The Dry Ice Method

This method is a bit different and somewhat more advanced, so you’ll need to:

  1. Put each food item in a separate freezer bag, making sure it’s evenly spread, not ending up in the corners.
  2. Take your time to ensure the bags are airtight.
  3. Grab an ice cooler and put the bags at the bottom.
  4. Put on a pair of gloves and add dry ice on top.
  5. Add another layer of food if you have more, then another layer of dry ice.
  6. Put the cooler in the freezer, with no lid on.
  7. Add the lid after 6 hours have passed.
  8. When 24 hours have passed, you can check the cooler for dry ice. If there’s none left, you can prepare your food for storage.
  9. Take the bag out of your cooler, and place them anywhere it’s convenient for you, like in the freezer or in a cool dry place like your basement or pantry.

PROS:

  • It takes less time than the Freezer Method
  • You can freeze more food items
  • When you reconstitute these, they taste better
 CONS:

  • You’ll need more equipment
  • The freezing process isn’t that thorough

     3. The Vacuum Chamber Method

This is the method we’ve been telling you about all along because this is the actual dry freezing process. So you’ll need to:

  1. Get a larger plate or a tray and put your food on it, making sure it’s spread out with enough space between the food items.
  2. It’s best to use a deep freezer and/ or set your freezer’s temperature at the lowest setting.
  3. Empty your freezer from any other items.
  4. Put the tray inside it.
  5. Don’t open the freezer at all while the food freezes, or that might contribute to the formation of water molecules in the form of ice crystals.
  6. Once the food froze during the course of a week, grab your vacuum chamber and set the pressure to 120 mTorr and the temperature to 50° F.
  7. Follow the instructions on your vacuum chamber, and remove the food items once the freeze-drying process has ended.
  8. Store your food in a cool, dry place until reconstituting it.

PROS:

  • The food lasts for years
  • The water is eliminated 98%, so the food items are very compact and light now
  • It’s a thorough process
 CONS:

  • It takes a long time
  • A vacuum chamber is extremely expensive
  • The vacuum chamber is quite heavy
  • You can’t freeze a lot of food at once
  1. The Inca Method

This is the most rudimentary dry freeze method of all, but it might still be incredibly useful if you’re having an emergency, such as being out of food in the wilderness. So:

  1. Grab your food and freeze it overnight if you have a camp freezer.
  2. If you don’t have a freezer with you, place it in a cold place, safe from insects and animals.
  3. When the morning comes, expose it to the sun or a campfire, to mimic the heating part of the process.
  4. Place your food items in airtight bags.
  5. Put these bags in a cold, dry place.

PROS:

  • It’s great for emergencies
  • You don’t need a lot of tools
 CONS:

  • You depend on favorable weather, like extremely cold nights and very hot days.
  • You need to take very thorough protective measures from wildlife
  • You can’t store the food for long
  • You can’t use it on all types of food

The Reconstituting Process

Now that you’ve chosen your weapon, you can de-freeze the food anytime you like to.

The steps you need to take are the following:

  1. Depending on how much food you have frozen, boil 3 or more cups of water in a pot and remove the pot when it starts boiling.
  2. Get your food items out of their packs and put them in a bowl.
  3. Start pouring water on top of the food, and wait for it to swell up.
  4. Don’t pour all the water at once, and make sure to stop immediately after the food items look as good as new.

Final Thoughts

The dry freezing process is pretty easy once you get the hang of it and understand how it works. So in this article, we’ve taken you through a series of methods that allow you to freeze-dry any food you like, but we’ve also discussed some of its advantages.

Now, you’re in the limelight: why do you want to try dry freezing? Which of its benefits convinced you? Which method are you going to use? And once you’ve done your first try, come back here and tell us how it all went. The comment section awaits!

ABOUT THE AUTHOR

Russell McCarty

Russell McCarty

Russell considers backpacking one of his great passions in life. He actually managed to transform his passion into a living becoming a professional adventurer. Russell loves long-distance backpacking and he enriched his portfolio with famous trails like the Alaska-Yukon Expedition or the Appalachian Trail. With thousands of miles under his feet, Russell is the expert to consult when it comes to how to prepare for a successful outdoor adventure.