.Steam Pressure Canning Overview
Source of Recipe
Vegetable Gardening Encyclopedia Typos by Dorothy Flatman 1995
Steam pressure canning is the method used for home canning of low acid foods, such as vegetables, meat, poultry, seafood, and soup. Mixed vegetable recipes that contain tomatoes are also considered low acid. In steam pressure canning, you pack jars with hot or cold food and place them on a rack in a pressure canner. Then you add water as the manufacturer directs, seal the canner, and heat it. The steam created is under pressure and reaches the superheated temperature of 240 degrees F, which is capable of killing the harmful byproducts of the botulism bacteria. Most vegetables by be either cold or hot packed.
Remember too, that altitude can affect the pressure in your steam pressure canner. Check the chart to find what adjustments may be necessary at your altitude. If your pressure canner has a weighted gauge, use 15 pounds pressure at all altitudes over 2,000 feet.
ALTITUDE IN FEET PROCESS AT PRESSURE OF 2,000 -
3,000; 11-1/2 pounds 3,000 - 4,000; 12 pounds
4,000 - 5,000; 12-1/2 pounds 5,000 - 6,000;
13 pounds 6,000 - 7,000; 13-1/2 pounds 7,000
~ 8,000; 14 pounds 8,000 - 9,000; 14-1/2 pounds 9,000 - 10,000; 15
pounds
A pressure canner is a large, heavy metal utensil that heats water under pressure to create steam. The steam is hotter than boiling water and can cook food to the 240 degree F needed to kill dangerous botulism bacteria. Although the initial expense of a steam pressure canner may seem high, it should last you through many, many years of gardening and canning. In addition, it can be used for quick cooking may other foods.
Steam pressure canners come in several sizes, ranging from 8 to 22 quarts in capacity and holding 4 to 7 one quart jars, or many more pint jars of food. You may already have a pressure cooker, or saucepan pressure cooker. You can use this for processing if it will hold pint jars, if it has an accurate gauge, and if it will maintain 10 pounds of pressure. Add 20 minutes to the processing time given in the recipe if using a regular pressure cooker, or saucepan pressure cooker. Pressure canners and cookers differ slightly in construction; one type has a dial gauge, another a weighted gauge. Always follow the instructions that came with your particular canner to the letter. Always check the gasket and locking mechanism and clean all parts as the manufacturer directs.
TESTING THE DIAL GAUGE Dial gauges must be checked each canning season. The home economist at your local Cooperative Extension Service Office can tell you where and when you can have the dial tested. If the dial varies more than 5 pounds per square inch either way, get a new one. If the variation is less than 5 pounds, adjust pressure using the chart below. Weighted gauges don't need to be tested, but they must be kept clean.
If gauge reads low by 1 pound; Process at pressure of 11 pounds.
2 pounds; 12 pounds.
3 pounds; 13 pounds.
4 pounds; 14 pounds.
If gauge reads high by 1 pound; Process at pressure of 9 pounds.
2 pounds; 8 pounds.
3 pounds; 7 pounds.
4 pounds; 6 pounds.
Handle the dial gauges with care. NEVER rest the cover on the gauge and never turn the cover upside down over a full pan with the gauge attached, because moisture could enter the gauge and rust it.
MAINTAINING PROPER HEAT LEVELS: Big pressure canners may cover the range burners completely. Set the pressure canner on the burner to be sure there's enough air space to keep gas burners on or to prevent the enamel of the range surface around the electric unit from growing too hot. If a pressure canner seems too snug against a burner, lift it up 1/4 to 1/2 inch on asbestos blocks or an extra gas burner ring, so that heat and air can circulate. (Make sure the asbestos blocks or extra gas burner ring does not itself cut down the air space of the gas burner or block the heating of the electric unit.)
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