Brining was originally used for food preservation before refrigeration was available. In the old days food availability was seasonal. One food might be available during the spring and another might be available in the fall. If you are going to enjoy these seasonal foods year round you will need a way to preserve them. Brining is one such solution that allows you to preserve certain foods for extremely long periods of time if needed.
Using a Brining process is basically a subset of the pickling process, just salt without sugar or vinegar added. So how does brine act as a preservative? Salt is the preservative in brine and it works by actually removing water from the cells. If a cell is unable to intake more water they die. It's as simple as that. That is why covering meat in salt has been used for ages to preserve meat. The brine solution works the same way. The advantage of using brine is that by submerging food in a brine solution you are assured of 100% coverage. Rubbing on salt allows for the possibility of missing a spot. Over time the food and the brine will use the process of osmosis to eventually equalize and both be the same salinity. The brine will decrease slightly and the food will increase in salinity.
Before getting into how to brine food, let's first retouch on the differences between brining and pickling. The difference between brining and pickling is that brine preserves food in a salt solution while pickling preserves food in a salt AND either sugar or vinegar solution.
So in a nutshell, to brine food it is simply covering a meat or vegetable in a saltwater solution for a period of time.
When preserving food by brining you must completely cover the food you are to preserve. Often foods will have a tendency to rise to the top of the container, thereby exposing part of the food to the air. This is a bad thing and opens the possibility that the container will be contaminated as bacteria consume and reproduce on the exposed food. A small stone or piece of plastic or glass can be used to prevent the food from surfacing. Just place the flat rock, piece of glass or a piece of plastic on top of the food and when the lid is secured the rock or plastic will hold the food below the surface of the liquid as the lid prevents the food from pushing the rock up past the water line because the lid holds the rock down and for this to work obviously the brine level should be very close to the top of the container. You want very little air left in the non-metal container. Do not substitute metal for the rock or plastic piece.
Old school methods of making the brine solution were to add salt to the brine until an egg will float. Another method is to add salt slowly while stirring until the salt no longer dissolves in the water. Another method is to use at least one cup of salt dissolved in four cups of water. This will get the solution well above to over 10% salt, which is beyond the concentration that most bacteria can handle. When the salt content of a solution is high like this most bacteria will rupture and therefore die.
Ten percent may not sound extremely salty, but that is actually three times saltier than ocean water and this solution will be significantly saltier than that.
The process of brining is very simple once you have your solution of brine. Simply place the meat or vegetables in a container, usually a jar with a screw on lid but a clay jar with a lid sealed with something like lard works as well. Then the brine is poured into the jar until the jar is full to the top with little air space above the brine level. Place your spacer, the rock, glass or plastic piece on top of the food and screw on the lid. Do not screw on the lid super tight as you actually want any pressure that builds up in the jar to have some way to escape without the jar exploding.
Tip: I soak my venison in icewater for about 5 days to draw out the meat before butchering and freezing. This is to draw out the blood from the venison to make it taste better. The meat must be kept in a slurry of ice water and the water should be partially drained as it becomes red with blood.
This is easy to do if you have ice. If you however do not have ice but have plenty of salt you can do the same thing for a day or two by simply keeping the meat in a brine solution before removing the meat discarding the water and continuing with the brining process. Some processes of preserving meat by brining in the past used this step although it is unclear to me if they did this step for food preservation or food quality purposes.
You can greatly increase your chance of successfully brining food by bringing the brine solution to a boil then letting it cool a bit before pouring slowly into the food filled jars.
Another step that further ensures success is to place the jars in a large pan or pot with high sides. This can be done while they are still warm if you boiled the brine solution before filling the jars. Place the jars in the pan/pot and add water to the pot. Then add heat to the pot/pan to raise it temperature. Bring the water to a boil slowly. Then let it cool naturally. Lids should be off or loose during the process. After the water has cooled secure the lids. Add more brine to the jars if needed to bring the brine level back near the top of the jar.
The food will be brined after a variable amount of time depending on what exactly it is that you brined. Thicker, bigger food and meats require longer brining times than smaller vegetables. Figure a two-week minimum before opening any of the jars.
If after a couple of weeks a white skin forms on the surface of the brine then something has gone wrong and that jar should probably be discarded.
When brining meats it takes time for the brine to make its way to the center of large cuts of meat, so meat is often cut up before brining. If the temperatures are cold it is possible to slow down the process of rotting by basically refrigerating the meat. If the meat is kept cool then that gives more time for the brine to penetrate before the meat spoils. So during cold times it is easier to brine larger cuts of meat without the need to cube it up.
For those of you that are worried about doing larger cuts of meat, fearing rot even with cold temps. You can either cut the meat into thinner pieces or make large cuts into the meat so the surface is never far from any part of the meat.
Brining just in the solution as described will preserve the meat about a month. For truly long term storage you need to spread a layer of salt on the bottom of the container and then add meat and salt until the container is completely full with as much salt as possible. Then a brine solution is poured into the container as described above and closed.
This takes lots of salt and basically requires access to the sea to have enough salt available in a SHTF situation.
The meat will need to be soaked in fresh water for at least two hours before use or the salty taste will be over powering.