It Solves the Problem of Low Acid Foods
And what is the problem with low acid foods? Nutritionally, there is nothing wrong with low acid foods. They do, however, present a problem to those who wish to do home canning. Pressure canners provide a solution.
The manufacturer of the Presto Pressure Cooker/Pressure Canner provides an explanation:
"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 212¼F, 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 212¼F. 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 240¼F. This temperature can only be achieved with a pressure canner."
So, if the question were to be asked:
Is There Something Fishy About Pressure Canners?
The answer would be, "You Bet!"
A pressure canner allows you to process fish as well as meats and low acid fruits and vegetables. This is something that is not recommended for a standard water bath canner. The difference lies in the higher temperatures which can be generated with a pressure canner. These will kill not only harmful bacteria, but also the spores that some of these bacteria produce. This is the only safe method of preventing the growth of the deadly botulinum toxins.