Pressure Canning. (pressure canner)

Pressure canner
The United States Department of Agriculture, Washington, D.C. recommends the Pressure Canner as being the only safe method for canning low-acid foods—vegetables, meats, and poultry.

There are invisible microrganisms present all around us. Fruits, vegetables, and meat contain these microrganisms naturally, and 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 interrupts 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, the bacteria thrive on low-acids in the absence of air. For a safe food product, low-acid foods need to be processed at 240˚ or higher, temperatures only achieved with a pressure canner.

In pressure canning, some of the water in the pressure canner is converted to steam, which creates pressure within the canner. As pressure increases, temperature increases, 5 pounds pressure—228˚F, 10 pounds pressure—240˚F, 15 pounds pressure—250˚F. This pressurized heat destroys the potentially harmful bacterial spores. As the jars cool, a vacuum is formed, sealing the food within and preventing any new microorganisms from entering and spoiling the food.

As a safeguard against using canned foods which may be affected with spoilage that is not readily detected, pour all low-acid foods (meats and vegetables) into a saucepan and boil 10 to 15 minutes before tasting or using.

Many times odors that cannot be detected in the cold product will become evident by these methods. If, after boiling, food does not smell or look right, discard it without tasting.

MASON JARS: While there are many styles and shapes of glass jars on the market, only Mason jars are recommended for home canning. Mason jars are available in 1⁄2 pint, pint, and quart capacities with threads on which a cap may be screwed.

CLOSURES FOR MASON JARS: The two-piece metal cap consists of a flat metal lid held in place with a screw band. A rubber compound on the underside of the lid forms a seal during processing. Follow the closure manufacturer’s directions
for using the two-piece cap and for testing for a proper seal. If the closure has not sealed, completely reprocess or use the food immediately.
pressure canner

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