Anyone who is going to be growing their own food also needs to know how to preserve it. This was a normal part of life for our ancestors, way back when; and it is an important survival skill for preppers to know. Wasting food, when there isn’t enough to go around, is almost criminal. But worse than that, it can make it harder to survive.
There are a number of common food preservation techniques you can learn, such as canning and drying of food. But one of the interesting things we encounter in just about any of these, is the use of salt. That common denominator is because salt is a natural preservative. We find salt in use in canning, dehydrating, curing and smoking. Obviously there’s a good reason for that.
But just how can salt preserve food?
Bacteria, the biggest thing we’re trying to protect food from, when we preserve it, requires a moist environment. That’s key to how salt works as a preservative, as salt helps to dry out the food, to the point where bacteria can’t survive.
Take a piece of meat sometime and cover it with a layer of salt. Within minutes, the salt will be soaking wet. Where did that moisture come from? It came out of the meat’s cells, following what is known as “osmosis.”
While the word osmosis is used in casual conversation in a number of different ways, it has an actual scientific meaning. In this application, that definition would be that osmosis is the movement of water molecules through the semi-permeable cell membrane, from a region of low salt concentration to an area of higher salt concentration. In doing this, it lowers the water content of the meat’s cells.
Since osmosis is a law of biology and chemistry, it really doesn’t care what sort of cells it is getting the water out of. The majority of that water comes out of the meat, because that is the largest quantity available. But bacteria are cells too, so any bacteria which are present in the meat or on its surface will lose water as well. Once they lose enough water, they will die.
So salt will kill bacteria directly, keeping our food safe. Taking this a step further, food which is salted and then dehydrated is not only bacteria free, but any bacteria landing on the surface of that food will die quickly. The dry food is a hostile environment to the bacteria and the presence of salt helps speed up the process of killing the bacteria by drawing water out of it.
Salt alone isn’t enough, as salt won’t keep most insects and rodents out of food, although it will keep ants out of the food. Proper packaging is required to keep other types of insects and rodents out of your food supply; something that they can’t just gnaw their way through.
The same preserving effect happens with sugar, in the same way. But sugar is only is used in the preservation of fruit. Fruit naturally contains sugar, but additional sugar is used at some times. In addition, some fruits are acidic, which also adds to the hostility of the environment for the bacteria, although it can attract ants and bees.
Be sure to have a goodly stock of both salt and sugar in your stockpile; not only for eating, but for preserving food that you grow and hunt.
 This definition has been modified to deal with the specific circumstances, salt and a cell wall. The fuller definition involves the movement of a solvent (water is a solvent) through a semipermiable membrane from an area of low solute concentration (the salt) to one of higher concentration.