When sardines are freshly caught they are actually a small fish called a herring. These are usually caught by the thousands in fishing nets. Herring has always been a popularly eaten fish, especially in parts of Europe, but they weren't canned for everyone to enjoy until the mid 1800s.
It is once they are canned and sold at the store that they are called sardines. Sardines are used for many things. Sardines are of great nutritional value, and in fact, we should probably eat more sardines as they are high in vitamins, minerals and omega3 oils. Herrings were first canned over two hundred years ago by Napoleon, who needed a way of preserving fish for his troops. Today, sardines are used in recipes, or eaten alone.
Canning sardines is fairly easy and you will only need a few items: The fish, lemon juice, mustard, canning salt, cooking oil, and a pressure cooker. The canning process is still very similar to that done over two hundred years ago, although it is probably cheaper now to go to a grocery store and buy sardines. Still learning how it is done is interesting.
The first thing you have to do is clean the herring. You will need to remove the head, the internal organs and scale the fish. You can do this by slitting the fish at the indention just above the tail and moving up to the throat. Insert your fingers and pull the viscera out. You can use the knife to help you out. Then cut the head off with a quick slice. Make sure your knife is nice and sharp.
Then you want to put the fish in the canning jar. Make sure they fit snugly but not too tightly and compact each fish as you add another. Next you want to place the cup of water into the jar and add the mustard.
Then add about 3 tablespoons of natural lemon juice and a teaspoon of canning salt. Try to use natural lemon juice as it adds a much fuller flavor to the herring. Once you have done that you will want to fill the rest of the jar with cooking oil but stop when you are about an inch away from the jar lid line.
Replace the jar lid tightly and line the jars into the pressure cooker. Be sure to add water into the pressure cooker and cook at 14 lb. pressure for an hour and 15 minutes then let your fish cool, and store.