Home Survival StrategiesFood & Water Freeze Drying

Freeze Drying

by Chris Weatherman

The advent of the personal freeze dry machine has changed home food storage in a major way. No longer are we relying on the big freeze dry companies to package our long-term foods for us. Now, we can do it at home and control just what goes into our food. This alone is reason enough to purchase one of these machines.

Knowing exactly what is in your food offers a piece of mind that buying prepackaged foods cannot. And it’s not just knowing what’s in the food but having the ability to pack foods your family already enjoys is another huge benefit. During times of crisis we are under enough stress. Having to exist on a diet of unfamiliar or all together foreign foods will only add to it. Being able to reach into your food storage and pull out a package of lasagna that you prepared and stored will provide comfort and a sense of normality commercially produced foods cannot.

However, having the machine isn’t enough. You’ve got to use it and more importantly, learn its limits and the nuances of freeze drying. Safety is the biggest concern. The last thing we want is to make the entire family sick from eating improperly stored and prepared food. With this in mind, be sure to follow your manufacturers instructions and recommendations. If there is any doubt about the safety of something you’ve stored, throw it out.

The Food

As already stated, the biggest benefit of home freeze drying is storing exactly what you want. Take some time to consider just what you’re going to store. When it comes time to acquire the food, buy the highest quality you can find. This goes for meats and dairy as well as vegetables. You want the freshest and best quality you can lay your hands on.

Don’t forget about leftovers! Freeze drying is a perfect way to deal with leftovers. Keep this in mind and prepare meals larger than you normally might so you can put some away for later. Afterall, the machine is always there and running it means you’re increasing your larder.

The Process

Freeze drying is a simple process. Water can only exist in a vacuum in two states –  a solid or a gas. The machine will freeze the food to an extreme sub-zero temp. Once the food is frozen, the rack will slowly warm the food. The ice will begin to melt and turn to water vapor which then refreezes to the inside of the chamber. This process is repeated serval times until all the water is removed from the food.

Freeze Drying Process diagram for freeze drying food

When it comes time to get down to work, always observe proper food handling measures. Avoid cross contamination to prevent issues. For this reason, I try not to do meats and veggies in the same run. I also avoid doing raw meats with anything that is already cooked. If, for instance, you want to run a batch of raw ground beef, don’t toss last nights leftovers in. If you feel you just can’t run the machine with an empty tray, put the cooked food on the top rack as a precaution.

Surface area is the key to freeze drying. The more surface area the product has, the faster it will dry. I’ve personally done beef that was cut a half inch thick. These steaks came out great. But most often, I cube the meat up into pieces about three-quarters of an inch. Place the food on the tray so that the pieces are not physically touching, but as close together as possible.

I prefer to slice vegetables into pieces about a quarter-inch thick. And any vegetable can be freeze dried. I’ve run carrots, spinach, potatoes (these dehydrate nicely as well) asparagus as well as many others. Vegetables take very well to the process and finish quickly.

Fruits can be tricky. We’ve probably all had freeze dried pineapple. But I have yet to turn out a good batch. There is a learning curve and you will have to figure out the tricks to your machine. Most fruit has a lot of water in it and it can take a long time to get the fruit completely dried. When the machine says it’s done, open it and check a piece. If it doesn’t snap like a dry twig, it’s not dry enough. You’ll have to run another dry cycle.

Meats take to the process at different levels. Almost all cooked meats will quickly dry and are rather straightforward. Raw meats however, take a little learning. Personally, I’ve found raw chicken takes quite a bit of time to get dry. Just check the largest piece in the batch for dryness. If it bends or seems spongy, run another dry cycle.

Other items like lasagna or cooked spaghetti take very well to the process as well. These are the easiest foods to preserve and prepare as well. Foods like these can quickly be rehydrated and prepared for a fast, fulfilling meal. Almost any meal your family enjoys now can be processed and stored.

As you begin your journey into freeze drying, you’ll learn a number of tricks that will speed things up and make a better finished product. One of the best ways to speed the process up is to pre-freeze the food. Load it into the tray and place the tray into the freezer. Give the food a few hours to freeze and start your machine. Once the temp is down in the chamber, transfer the trays of food to it and close it up. This will dramatically cut down the time it takes to complete a cycle.

The absolute most critical part of the process is when the machine finishes a cycle. You need to be there when it completes. When the cycle completes, the food itself will not be cold, it’ll be warm from the drying process. If you leave it too long it will start to freeze again and if you remove it, this cold food will condense and pick up moisture from the air. If this is the case, you will have to run another dry cycle.

Once the food is done remove the trays. Take the largest piece of each kind of food processed and test it for dryness. The piece should snap like a dry twig. There shouldn’t be any bending, the piece should not feel spongy or pliable at all. If the food breaks with a crisp snap it’s good to go. Now it’s time to package.

You can store your food in jars or mylar bags as you would anything else. If you’re using jars, you can vacuum them down and add desiccant packages as well. You can also use conventional vacuum bags. Just follow your normal process. It’s important to keep in mind that moisture is the greatest enemy to your recently dried food. With that said, oxygen and light are also the enemies of food storage so take the necessary precautions.

Now that your food is processed, you’re not done yet. You need to address the maintenance of the machine. It is best practice to drain the oil from your vacuum pump after each use. You can then filter the oil and put it back in, or you can replace it with new oil. When the system is running, the pump will pick up water and this finds its way into the pump. The water dilutes the oil and can also rust internal parts. It’s very important to get this done immediately after the process is done.

I use a filter to clean my oil. When the process is complete, I drain the oil into the top chamber of the filter. It will filter into the bottom chamber very slowly. This takes quite a bit of time to complete. To speed things up, I refill the pump with new oil. Once the oil in the filter was done, I pour it into a clean jar. Then, I drain the pump into the filter and pour the previously filtered oil back into the pump. Now, I am able to keep the pump going.

There will be a little oil loss to the filter so it’s important to have a jug of oil on hand to top off the pump. This is the most critical step in the maintenance of the system. There are inline filters you can add. I had one for a while. But forgetting to turn one of the valves and starting the pump caused the front seal of the pump to rupture. It blew oil all over the kitchen, even the ceiling. It was then that I decided to use a manual filter. This takes more time, but there’s no chance you’re going to ruin your pump. With this in mind, it’s a good idea to keep some spare parts on hand for your pump. Check with your pump manufacturer for the appropriate parts.

Having your own freeze dry machine can greatly increase your ability to store high quality food. You will be in total control of what’s in the food you store. You’ll be able to store the foods your family like to eat and most importantly, ensure there are no allergy issues. Food is freedom and having the ability to freeze dry your own food offers you a significant level of security.

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