Unless you're making very small, quickly eaten batches, you may want to invest in a pressure canner.
Here's an excerpt from "Presto's" web page:
"If you're a novice to pressure canning, this outline will give you a basic knowledge of the terminology and instruction of canning.
The key to successful canning is understanding the acidity and spoilage factor of the food you wish to can, as well as the acceptable canning methods to process those foods.
There are two types of food, categorized as low-acid (vegetables, meat, poultry, and seafood) and high-acid (fruits and tomatoes). Both can be successfully canned by pressure canning.
However, pressure canning is the only method recommended safe for canning low-acid foods according to the United States Department of Agriculture. Boiling water method is another recommended method of processing, however this method is only acceptable for some foods. Always follow the processing method stated in the recipe.
Invisible microorganisms are present all around us. Fruits, vegetables, meat, poultry and seafood contain these microorganisms naturally. Yet, they are not a problem unless food is left to sit for extended periods of time, causing food spoilage. This is nature's way of telling us when food is no longer fit to eat.
There are four basic agents of food spoilage – enzymes, mold, yeast, and bacteria. Canning will interrupt the natural spoilage cycle, so food can be preserved safely. Molds, yeast, and enzymes are destroyed at temperatures below 212° F, the temperature at which water boils (except in mountainous regions). Therefore, boiling water processing is sufficient to destroy those agents.
Bacteria, however, are not as easily destroyed. The bacteria, Clostridium botulinum produces a spore that makes a poisonous toxin which causes botulism.
This spore is not destroyed at 212° F. In addition, bacteria thrive on low acids in the absence of air. Therefore, for a safe food product, low-acid foods need to be processed at 240° F. This temperature can only be achieved with a pressure canner."
The rest of the article can be found at:
http://www.gopresto.com/recipes/canning/index.php