UNDERSTANDING THE DIFFRENT METHODS OF PRESERVING FOOD
​Survival food comes in many shapes and sizes. It is prepared for a long shelf life through various means. So first off let's start with the different types of survival food and how they are prepared. 

FREEZE DRIED FOOD:
Freeze Drying is a fairly simple process. The food is placed on large racks inside of a vacuum chamber. The temperature is lowered to below freezing and then slowly raised. The water in the food moves from a solid state to a gaseous state - maintaining the structure of the food and keeping the nutritional value.

DEHYDRATED FOOD:
Dehydrating has been a food preservation practice for thousands of years, dating back to at least 12,000 BC.[1] The Romans and Middle Easterners would dry fruits and vegetables in “still houses” which would use a fire to dry out and smoke foods.
Modern day dehydration isn’t that complex. A dehydration machine circulates hot and dry air across the food. This removes much of the water. The moist air is then dried so that water continues to be removed. The temperatures are high enough to remove water but not high enough to cook the food. Dehydrated food is usually withered and harder.

CANNING:
Canning is the process of heating the product at a specified temperature for a specific length of time (pasteurizing), and then vacuum sealing the pasteurized food in special glass jars designed for this purpose. It can be used with most foods, including fruits, vegetables, meats, seafood, and some prepared foods. Canning requires the purchase of reusable canning jars and rings, one-time use sealing lids, and some practice to learn the necessary and detailed steps.

VACUUM PACKING:
Vacuum packing is a method of packaging that removes air from the package prior to sealing. This method involves (manually or automatically) placing items in a plastic film package, removing air from inside, and sealing the package. Shrink film is sometimes used to have a tight fit to the contents. The intent of vacuum packing is usually to remove oxygen from the container to extend the shelf life of foods and, with flexible package forms, to reduce the volume of the contents and package.

These are some of the most common methods food is prepared for long term storage and each has its own pros and cons. In the next section I'll discuss them.



FREEZE DRIED FOODS

SHELF LIFE: 25 to 30 years
NUTRITIONAL CONTENT: Maintains most vitamins and minerals. Some will be lost over time, especially vitamin C.
WEIGHT: lightest of all methods. Easy to store and carry.
COOKING: Just need to add water, usually ready to consume in five minutes. 
COST: Typically the most expensive on the market. Freeze dryers can be costly to purchase for DIY. 

​DEHYDRATED FOOD

SHELF LIFE: 15 to 20 years
NUTRITIONAL CONTENT: fiber content & iron is not affected, other vitamins & minerals are broken down during the process & some are lost. Retained levels are less then freeze dried food in comparison.
WEIGHT: Weight is not reduced as much as freeze dried, but there is still a significant reduction.
COOKING: Need to add boiling water typically and can take anywhere from 15 minutes to four hours to be ready for consumption on some items.
COST: Dehydrated foods are significantly cheaper then freeze dried foods & for the DIY a food dehydrator is reasonably price. Good option for those are prepping on a tight budget.

CANNING

SHELF LIFE: Optimal quality is one year. Taste will often start to degrade. Best advice is if you are concerned, don't eat it.
NUTRITIONAL CONTENT: Vitamin & mineral content will lose about 10%-25% over the course of shelf life. Will retain more if produced is canned closer to harvest date.
WEIGHT: Bulky & the heaviest of all methods to store and transport.
COOKING: ​Already cooked and can be eaten out of the jar.
COST: Typically the most expensive on the market. Freeze dryers can be costly to purchase for DIY. 

​VACCUM SEALING

SHELF LIFE: Will extended refrigerated food & frozen food by 2-3 years. Will extend the life of pantry stored food, I.e. Rice & flour by 1-2 years.
NUTRITIONAL CONTENT: Nutritional value is not affected by vacuum sealing & normal nutrional loss occurs.
WEIGHT: Weight is not reduced as much as freeze dried, but there is a reduction.
COOKING: Food will need to be cooked if not already cooked.
COST: Vaccum sealers are inexpensive for the DIY and can be used for more then food. A very cost effective way to store refrigerated and frozen items. Also inexpensive way to store dry goods & extend their shelf life.