Freeze drying (also known as Lyophilization) is a method of preserving food in such a way that will prevent microbial growth in the food and drastically reduce its weight in the process. This is accomplished by a method which removes almost all the moisture from the food, leaving only approximately 0.5 to 3% moisture once the process is complete.
This process actually freezes a food to a very specific and very cold temperature (known as the “triple point”). At this temperature, the moisture in the food can go from a solid state (ice) directly to a gas state, without become liquid in between. This involves a very careful balance of cooling, heating, and carefully controlled atmospheric pressures to accomplish this feat of modern science. The food is usually dried twice prior to packaging for sale.
- Average Cost Per Ounce Prepared: $0.45/oz
- Average Cost Per Ounce: $1.85/oz
- Approximate Number of Days of Survival per $100: 4.4 Days
- Approximate Cost Per Day of Survival: $22.50
- Shelf Life: 7 – 25+ Years
- Typical Storage Conditions: Below 75 degrees Fahrenheit
- Ideal Storage Conditions: As cool as possible but above freezing.
A Note About the Above Calculations: The “Average Cost Per Ounce” is the average cost, per ounce, in its shelf-stable state. “Average Cost Per Ounce Prepared” is the average cost of the food once it is fully prepared. Freeze dried food typically requires adding water to allow re-hydration and consumption of the food. This is why your cost per ounce decreases drastically once it is prepared and ready to eat. A “day of survival” is based on consuming approximately 50 ounces of prepared food in a day. This should be sufficient to ensure you receive a 2000 calorie a day diet.
Most freeze dried foods are packaged in either large number 10 cans or smaller Mylar bags for distribution. The result of this preparation and packaging process is an incredibly shelf stable food that can last 20 years or more and still be just as delicious as when it was produced. Virtually any food can be preserved in this method. Complete meals can be cooked and consumed just by opening a bag, adding boiling water, and eating a few minutes later. Lasagna, scrambled eggs, chicken or anything else you can dream up is available.
Backpackers, hunters, and preppers alike love this type of food because they are incredibly light weight since most of the water is removed. Also, full meals can be prepared in the field just by adding boiling water. It’s easy, shelf stable, and incredibly delicious. So what’s the down side? The biggest downside is the price, as this process isn’t easy or cheap to perform.
Pro’s and Con’s of Using Freeze Dried Foods as an Emergency Food Source
At first glance, freeze dried food may seem like the perfect solution to preparing your family for an emergency where food may be difficult to get. In many ways it can be, but there are some drawbacks that you should be aware of.
- Generally light weight and easy to carry.
- Easy to prepare; just add boiling water.
- Extended shelf life (7 to 25 years or more).
- Wide variety of food available including: vegetables, meats, wheat, dairy, and desert products.
- Expensive when compared to many alternatives.
- They can sometime lack on taste.
- Multiple packages often need to be used to obtain variety in a meal (each item is packaged individually).
- A significant amount of water is always needed to prepare.
The largest draw back here is the price. Most of us do not have the means to spend thousands of dollars for a professionally packaged freeze dried food supply for our family. Dried foods, for example, can provide significantly more calories for the dollar and last just as long. However, freeze dried foods comes in a much larger variety than if you had to stick to only dried foods. Also, you will need a significant supply of water to prepare freeze dried foods. If you are likely to be in a situation where water sources are limited, this may not be your best option and you may want to consider storing MREs instead.
The biggest advantage for freeze dried foods is the ease of preparation. Many manufactures sell whole meals packaged individually in Mylar bags (such as Mountain House or Wise Foods). To prepare these foods you usually just need to cut open the bag, add boiling water, and wait a few minutes. Then open the bag and eat. These days, there are fairly complex dishes that come in this format such as lasagna and full egg breakfasts with bacon.
I will point out that while freeze dried food can lack a little on taste, the modern versions are very much improved with the quality of taste. A very delicious meal can now be had in freeze dried form compared to years ago.
We at SuperPrepper.com are not doctors or scientists. We are merely a group of passionate preppers sharing what we learn as we go. We do not guarantee that you will experience the same shelf life as displayed on this page. When in doubt, do not eat it! Always consult with a professional first.
Shelf Life: Official vs. Actual
Many of the individual packages of freeze dried foods will have a printed on shelf life of 5 to 7 years. We call this the “official shelf life.” However, by almost all accounts, this is extremely conservative. Even the manufactures themselves will tell you that their foods will easily last over 25 years. One of the largest manufacturers, Mountain House, now guarantees all of their freeze dried foods to 30 years (except Ice Cream products & Cheesecake Bites).
Most reputable manufactures will pump nitrogen into their food packages or cans prior to sealing them to ensure that all the oxygen has been removed. This is one additional step to preserving the food. If the food in question is manufactured by a reputable company and packed with the use of nitrogen, you can be confident that it will likely still taste great in over 30 years from the date of manufacture if stored in average room temperatures (65-72 degrees Fahrenheit).
|Sealed in Mylar bag or can.||25+ Years||Ensure it’s stored in consistent temperatures below 72°F.|
|Opened package and food exposed to oxygen.||7 Days||Keep cool and away from sunlight.|
|Fully prepared with water added.||1 – 3 Days||Treat like standard household leftovers. Keep cool.|
Once a package or can of freeze dried food is opened and exposed to oxygen, you should ensure you use the contents within about a week. Once you have fully cooked it for consumption, treat any left overs as you would regular household left overs and refrigerate.
Ideal Storage Conditions
Microbial growth is what spoils any type of food. Freeze dried foods are no exception. So to ensure the maximum amount of shelf life you want to ensure you inhibit the microbial growth as much as possible. Below are the ideal storage conditions to ensure your freeze dried foods stay fresh for the longest period of time.
- Moisture: Since freeze drying is based on removing as much moisture as possible from the food, it should be obvious that you want to keep your food away from outside sources of moisture to ensure maximum shelf life. The best way to do this is to simply ensure that the packaging stay intact (weather Mylar bags or number 10 cans).
- Light: Aluminum cans will effectively block out almost 100% of light, however Mylar bags will block out varying degrees of light based on how thick it is (the thickness of these bags is gauged in “mils” – the more mils, the thicker the bag is). Here you can find a chart of the thicknesses of various freeze dried food manufacturer’s Mylar bags. Keep your food in a dark place, regardless of the packaging to ensure maximum shelf life.
- Oxygen: Keeping the packaging or can sealed is the only way to ensure oxygen is kept separate from the food. Store your food somewhere safe from rodents or other critters that may damage the packaging.
- Temperature: Keeping your food as cool as possible (but above freezing) will ensure maximum shelf life. Also it is important to reduce temperature swings as much as possible. A room near the center of our home without windows (such as a closet), a basement, or a cellar are the best choices since they generally have realtively stable temperatures.
Storage Temperature to Shelf Life
Since freeze dried food manufactures generally package their foods in either Mylar bags or sealed aluminum cans, moisture, light, and oxygen levels are generally kept in check. Therefor the biggest impact that you can have on the shelf life of this food is to ensure as close to optimal storage temperatures as possible.
Below is a table of the storage life you can expect at various temperatures. Keep in mind that keeping temperature fluctuations to a minimum is important as well.
Storage Temperature to Shelf Life of Freeze Dried Foods
Note: This is just a general guideline to show the relationship of temperature to storage life and is not exact. Contact the manufacturer of your specific brand emergency food for more exact numbers.
The numbers depicted on this table are fairly conservative. Generally, these foods are packaged by manufacturers understanding they will be stored at room temperature (65°F to 72°F). It is generally safe to consider your freeze dried foods to still be good for consumption for 25 years or more when stored at room temperature.
Video: Preparing and Taste Testing Freeze Dried Lasagna
Aside from the their relatively expensive price, freeze dried foods are an excellent way to store significant amounts of food away for your family in an emergency. These foods are easy to prepare, very light to carry in a pack, and boast some extremely impressive shelf life numbers. They do require significant amounts of water to prepare so this type of food is not ideal if you are likely to be using it in an environment with limited water. Take you time and compare various suppliers and as always remember to diversify and purchase other types of food preparations as well (canned goods, dry foods, or MREs).