Freeze-drying is one of many great ways to prepare food for long-term storage. If you are prepping for emergencies, you should highly consider adding freeze-dried foods to your DIY long term food storage plan.

Freeze-dried food stays fresh for about 20-30 years when stored properly in Mylar bags with oxygen absorbers. Normally, it is best to store dry goods in Mylar bags, but freeze drying allows you to store fruits, vegetables, meats, dairy products, and even whole meals in Mylar bags!

So, with the help of a freeze dryer, you can add foods to your supply that you would otherwise not be able to prep long-term.

In this blog post, we will go over the basics of freeze drying as well as the 5 steps of the freeze-drying process. So, let's get started! 

Freeze-Drying: An Overview

freeze-dried food

In scientific terms, freeze-drying is known as lyophilization. It is the process where water in its solid state directly converts into a gaseous state, skipping the liquid state. 

When it comes to food items such as fruits or vegetables, the water in the fruit or veggies is bound to different components. When it undergoes freeze-drying, the bound water is directly converted to a gaseous state, which makes the food material become dry. 

During this process, no chemicals or preservatives are used, and the structure and nutritional value of the food item stays intact. There is NO chemical change, but rather a physical change! 

The process makes the food resistant to bacteria or spoilage, so it is safe to eat when stored properly in #10 cans or in Mylar bags.

Lastly, 99% of water is removed during the freeze-drying process. So, all you need to do to reconstitute the freeze-dried food is add some warm water. 

5 Steps of Freeze-Drying

Commercially, the freeze-drying process includes 5 steps. 

freeze-drying steps

  • Pre-Treatment
  • In this first step, the food item is inspected to see if there is any spoilage or bad bacteria. 

    The ultimate objective of freeze-drying food is to keep it edible and nutritious when reconstituted, so checking for spoilage is crucial. 

    Pre-treatment can also include partially or fully cooking the food to maintain the structure, taste, and nutrients when reconstituted.

  • Freeze Drying 
  • After the pre-treatment, the food is arranged on large trays and put in the freeze-drying machine. The temperature is lowered to -58 to -112 F. In this step, the bound water freezes and converts to a solid state.

    freeze-dried food

    This step is crucial as it converts all the bound water into a solid state, and keeps the structure of the food intact.

  • Primary Drying
  • After the freeze-drying process is complete, the pressure is lowered slowly to create a vacuum. We already know that water can’t stay in the solid state under a vacuum— it will convert to a gaseous state. 

    This process is also called sublimation. The food structure stays intact while the water is converted to vapor. The vapor is then removed from the chamber through filters, which also reduces the risk of rehydration. 

  • Secondary Drying
  • To ensure that all of the water content has been successfully removed, the temperature is slightly increased. This process takes hours or even days depending on what food item is being freeze-dried.

    freeze-dried food

    Secondary drying is crucial to ensuring that all moisture is removed successfully. The process leaves about 1-4% of water content in the food item. 

    When the secondary drying process is completed, the food is ready to be packed.

  • Sealing
  • The freeze-dried food needs to be kept away from moisture and oxygen. Hence, it is usually packed in Mylar bags or #10 cans. 

    If you are conducting the freeze-drying process on your own, be sure to use Mylar bags with oxygen absorbers to avoid spoilage. 

    Bottom Line

    As you can see, the freeze-drying process requires precision, but it is the best way to store food long-term without destroying it’s nutritional value. 

    It doesn’t use any chemicals or preservatives, nor does it chemically change the food. Instead, precise fluctuations of temperature and pressure are what help freeze-dry the food effectively.

    If you are looking to perform the freeze-drying process independently, you can use Wallaby Mylar bags with oxygen absorbers for storing your freeze-dried food items!

    We offer Mylar bag bundles which include oxygen absorbers and premium, sealable Mylar bags. These bags are perfect for storing your freeze-dried foods as they are engineered with an added internal layer of aluminum foil, which provides superior durability and puncture resistance. 

    Head to our website to see why thousands of preppers swear by Wallaby Goods Mylar bags.