Home canning season is nearly upon us and the water bath and pressure canners are being dusted off and readied for use. The goal of home canning is to preserve food for future use by preventing spoilage. The high water content of foods makes them very perishable for a number of reasons including: the growth of microorganisms, the activity of food enzymes, reactions with oxygen and moisture loss.
Most microorganisms (bacteria, yeasts and molds) are difficult to remove from food surfaces. Washing helps, peeling and blanching help even more, but it is vital to use the most current recommended processing procedures and times.
Whether a food should be processed using a pressure canner or boiling-water canner depends on the acidity of the food. Low-acid foods include high protein foods, and ALL fresh vegetables except tomatoes and must be processed using a pressure canner.
Pressure canners for home use were extensively redesigned in the 1970’s. Earlier models were heavy-walled kettles with clamp-on or turn-on lids. Today’s models are lighter weight, thin-walled kettles, most have turn-on lids fitted with gaskets, have removable jar racks, a dial-gauge, an automatic vent/cover lock, a vent pipe covered with a safety valve and a safety fuse. Only use canners that have the Underwriter’s Laboratory (UL) approval to ensure their safety.
There are two kinds of gauges to indicate pressure, dial and weighted. Weighted gauges indicate and regulate the pressure and are usually designed to ‘jiggle’ several times a minute or to keep rocking gently when they are maintaining a pressure of five, 10 or 15 pounds. Reading your manufacturer’s directions is the only way to know how to use your weighted gauge. These gauges do not need to be tested annually. Dial gauges indicate the pressure and usually have a counterweight or pressure regulator for sealing off the vent pipe to pressurize the canner. This weight should not be confused with a weighted gauge, it will not rock or jiggle. Pressure reading on a dial gauge canner are the only way to know the pressure in the canner.
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