The freezing of dry foods is a recent invention and many people discover its usefulness. What it means is that by freezing your food dry, all the moisture and water content of the food is removed. This is different from the traditional freezing. With this new method, the nutritional value of the food remains intact. This is exactly what you want when you camp for days or your access to the world is blocked for a week or more during a disaster. You need nutrition more than ever. Otherwise, the structure of the food changes drastically as it becomes hard crumbs.
You will need warm water to thaw and dry the food so that it becomes edible. There are some steps to follow for proper freeze drying, and we will discuss it in this article.
You should also know that foods with a high water content are the easiest to lyophilize. Such foods are fruits and vegetables, eg. Apples, pears, berries, even potatoes, carrots and peppers. Its structure remains intact and only the water content is eliminated. The interesting thing is that you can freeze dry other foods such as meat, pasta, oats, etc. Your imagination is your limit. First you will have to learn the method using fruits or vegetables, since it is easier with them. When you feel comfortable with the process, you can move on to other more complicated foods.
However, one must be aware of the lyophilization of meat. Do not perform this procedure when you have stored the meat in the freezer and removed it from there or after having bought it in the market. The meat should be lyophilized right after cooking. This is when all its properties are intact and will still be edible. If you freeze the raw meat dry and then, after months, you decide to eat it and melt it, it will still be raw. And make sure that the raw meat is not palatable.
The best way to freeze your food dry.
First of all, you do not need a super advanced technique to achieve these results. It is true that there are special vacuum machines that extract all moisture from food (and that happens quite quickly), but that is not mandatory. There are other ways to end freeze-dried foods.
Use the freezer! This is an easy way to have lyophilized foods. The process can last several weeks, but there is no more action on your part than just placing the food in the freezer and letting it work. Basically, you can cut the food into small pieces and place it in a perforated tray or similar (so that there is the least surface that covers the food).
During the first hours the food will freeze. Then the sublimation process begins (that is, the drying process). This takes much longer, from one to several weeks. You can test if the food is ready by taking a frozen piece from the freezer and let it melt. If it turns black, then it is not ready and you should let it dry more. When the food is completely dry, it should not change its color (especially black).
If the food does not turn black after melting and retains its original and natural color, then it is ready for the final step of storing it.
Another way to freeze dry foods is use dry ice (CO2). This procedure is similar in concept to the previous method. You can use the means of difference to achieve what you want. Basically, dry ice allows all moisture to evaporate from food, leaving it freeze-dried. In extremely cold environments there is almost no moisture in the atmosphere (as a reference, Antarctica has the driest conditions on Earth).
You will need a very large container, almost twice as much as the food that will freeze. Place the food in large plastic bags and close it (dry ice should not penetrate the package). Completely cover the food with dry ice.
Then place the container in the freezer. The container must have some holes so that gas and moisture can escape from the container. If there is no more dry ice inside the container, this is your sign that the food is ready. This should happen with 24 hours, so be sure to check regularly.
One warning: when doing the above, always wear gloves and protective clothing while handling dry ice.
You should store the food when it is ready and lyophilized. The best way is to store it in plastic bags, but be sure to expel the air, as it contains moisture. You do not want to keep the humidity closed inside with the food. This will accelerate the deterioration of food. You can use a vacuum packaging machine if you want to be meticulous. You should also be able to properly seal the bags, so that you are sure that moisture can not penetrate inside.
Another popular method is to use a special vacuum chamber but you will have to buy one if you want to use this method.
First, freeze the food in the freezer (a freezer would be even better) and make sure there is no other food inside; keep the food you want to freeze later. Let it rest for several hours. Avoid opening the freezer too often, as this will slow down the process, since ice crystals form very quickly when meats with frozen air moisten hot air.
When finished, remove the frozen foods and immediately place them in the vacuum chamber. Set it to 120 m Torr. The temperature should be 10o C (50o F). Again, the process should take at least 1 week, maximum a few more. Everything depends on the parameters and the amount of moisture in the food. When finished the sublimation, place the food in storage bags and close them well.
Then comes the time when we must tell you how to reconstitute your lyophilized foods. This process is possibly the easiest of all. You need boiling water (a cup or two) and add it to the food. It will quickly begin to become its original fresh form, since it is soaked with all the moisture that it eliminated following one of the previous methods.
Some more details and information about lyophilized foods.
These details may be of interest to you. When you freeze the food for the first time, it requires a temperature of around -18 ° C (-0.4s F). Then, to make the sublimation process happen, contrary to the obvious logic, a warm temperature is needed: it provides energy so that this process can be initiated. The ice crystals must evaporate, so a temperature of 35 ° C (95 ° F) is needed.
In addition, while drying in the vacuum vessel, very low pressure is used. It is necessary for water to pass almost immediately from one state (frozen or liquid) to another (gas) and, therefore, evaporate very quickly from food. Without this process, drying would take much longer under normal conditions.
Of course, in the traditional method (without using sophisticated machines), the freezing of food basically creates a vacuum around the water molecules. When the food is slightly heated (to dry), these ice crystals quickly turn into vapor and leave the surface of the food.
Another interesting fact is that water has only two conditions when placed in a vacuum chamber (or in any vacuum condition): it can be gas or a solid. As the food freezes (a vacuum is created), and then moves to a slightly warmer condition, the frozen water can only evaporate like a gas. The thing is that even if the food is not kept in super low freezing temperatures, it still remains in sub-zero conditions. That’s the key to keeping it frozen, and letting the water evaporate. This process is called sublimation that we mentioned earlier.
In fact, if you use the first method described above, you will not need anything special that only a freezer. The first stage is freezing. Then, the water passes to the second vapor condition and begins to evaporate. All other methods require special cameras or dry ice for these two conditions to transition from each other. As long as you know how water works, you should be able to better control the process.
In addition, any type of food can be lyophilized and you do not have to worry about the taste or odor once it is reconstituted. It is even believed that reconstituted lyophilized food tastes and smells even better than traditionally dry food. The process of drying by freezing is the one that preserves all the qualities and nutrients in the food. Add the boiling water only revives the food. The only nutrients that can be depleted a little are vitamins C and E, and folic acid. There is some amount left, but most can not stand this process.
Freeze-dried food can last for years. There are people and even markets that store food in this way, so they can remain almost intact for time and then be reconstituted when they need to be eaten or sold. This process is, in fact, very old and is being used by the Incas. They placed a piece of food overnight to freeze it and then kept it under the hot sun for a whole day to dry completely.
Freeze drying is also popular with hikers and campers, since the camp requires you to carry many things in your backpack. Food can take up a lot of space and make your backpack heavy. If you add some bottles of water and your main weight comes from food and water. Therefore, replacing traditional foods with freeze-dried foods is actually an excellent way to enjoy a week of trekking or camping without the heavy loads.
It is also highly recommended that everyone have at least one year of stored food for future disasters or economic crises. After all, you can not keep a simple basement with fresh canned foods, as they may not all fit together. Here comes the magic of lyophilized foods. Since 98% of the moisture in the food is removed, this also means that more than 90% of the food volume will be removed. This makes it ideal for long-term storage (away from moisture), as it takes up very little space.
If you do not want to freeze your own food dry, you can turn to the manufacturers who already sell them. One of these popular brands is Mountain House. It is particularly popular with tourists and campers, but if you need to store food, you can buy it in bulk. And do not expect them to sell only some lyophilized fruits.
On the contrary, they have complete meals such as lasagna, scrambled eggs, cottage cheese and almost everything you can imagine. The truth is that almost any type of food can be lyophilized. Some people even freeze dry ice cream. And to our surprise it worked.
This is why if you take your time and try one of the above methods, you can use your own imagination and freeze your favorite foods, instead of eating foods that you do not particularly enjoy.
And finally, you can freeze the dried meat. One of those very popular foods is dried meat. The process is the same and you end up with meat, full of all its inherent nutrients and it is so light that it is like a sheet of paper. You can also do the same with regular cooked beef. Then, cook the meat and then cut it into small pieces. Follow one of the above methods for lyophilization and you will end up with very small hard crumbs (almost like bread crumbs). It would not even look like beef, but by adding boiled water you will recognize the flavor immediately.
Consider freeze-drying every time you go camping or want to store some food for more uncertain days, or just experiment and see how easy it is to complete the process. It’s great to have less room to spare in the fridge when you need to store your food.
CONSERVATION OF FOOD