6. When the timed process is completed, turn off the heat, remove the canner from heat if
possible, and let the canner depressurize. Do not force-cool the canner. Forced cooling
may result in food spoilage. Cooling the canner with cold running water or opening the
vent port before the canner is fully depressurized will cause loss of liquid from jars and
seal failures. Force-cooling may also warp the canner lid of older model canners, causing
steam leaks. Depressurization of older models should be timed. Standard-size
heavy-walled canners require about 30 minutes when loaded with pints and 45 minutes
with quarts. Newer thin-walled canners cool more rapidly and are equipped with vent
locks. These canners are depressurized when their vent lock piston drops to a normal
7. After the canner is depressurized, remove the weight from the vent port or open the
petcock. Wait 2 minutes, unfasten the lid, and remove it carefully. Lift the lid away from
you so that the steam does not burn your face.
8. Remove jars with a lifter, and place on towel or cooling rack, if desired.
Selecting the Correct Processing Time
When canning in boiling water, more processing time is needed for most raw-packed foods and
for quart jars than is needed for hot-packed foods and pint jars.
To destroy microorganisms in acid foods processed in a boiling-water canner, you must:
•Process jars for the correct number of minutes in boiling water.
•Cool the jars at room temperature.
The food may spoil if you fail to add process time for lower boiling-water temperatures at altitudes
above 1,000 feet, process for fewer minutes than specified, or cool jars in cold water.
To destroy microorganisms in low-acid foods processed with a pressure canner, you must:
•Process the jars using the correct time and pressure specified for your altitude.
•Allow canner to cool at room temperature until it is completely depressurized.
The food may spoil if you fail to select the proper process times for specific altitudes, fail to
exhaust canners properly, process at lower pressure than specified, process for fewer minutes
than specified, or cool the canner with water.
Examples of Using Tables for Determining Proper Process Times
This set of guides includes processing times with altitude adjustments for each product. Process
times for 1/2-pint and pint jars are the same, as are times for 1-1/2 pint and quart jars. For some
products, you have a choice of processing at 5, 10, or 15 PSI. In these cases, choose the canner
pressure you wish to use and match it with your pack style (raw or hot) and jar size to find the
correct process time. The following examples show how to select the proper process for each
type of canner. Process times are given in separate tables for sterilizing jars in boiling-water, dial-gauge,
and weighted-gauge canners.