Pressure Canning
A home canning method that uses steam pressure to raise the interior temperature of jars to 240-250°F, high enough to destroy Clostridium botulinum spores. Required for all low-acid foods including vegetables, meats, and beans.
Pressure canning processes food in a sealed vessel under steam pressure, achieving internal jar temperatures of 240-250°F. These temperatures are unachievable in open water bath canning (maximum 212°F at sea level) and are required to destroy Clostridium botulinum spores in low-acid foods. All vegetables, meats, poultry, fish, and beans must be processed in a pressure canner, not a water bath canner.
The equipment is a heavy pot with a locking lid, pressure gauge (dial or weighted), and vent/petcock assembly. Jars sit on a rack inside; steam builds in the sealed pot until the desired pressure is reached and maintained for the tested processing time.
Equipment
Dial gauge canners: Show exact pressure on a gauge. The gauge must be tested for accuracy each canning season - extension service offices typically offer gauge testing in spring. An inaccurate gauge creates either under-processing (safety risk) or over-processing (quality loss). Presto is the major home brand.
Weighted gauge canners: Use pre-set weights (5, 10, or 15 lb) that jiggle when the correct pressure is reached. No testing required. Less precise but no calibration concerns. All-American is the major home brand; these are all-metal with no rubber gasket.
A pressure canner is not the same as a pressure cooker. Electric multi-cookers (Instant Pot) marketed for home canning have not been validated for safety by USDA or NCHFP as of 2024 - they may not maintain consistent pressure throughout processing and lack the capacity data needed to validate thermal processing. Use a stovetop pressure canner.
Basic Process
- Prepare jars and lids per tested recipe; fill with correct headspace
- Place jars on rack in canner with 2-3 inches of hot water
- Lock lid; heat on high until steam vents steadily from petcock
- Vent steam for 10 minutes (purges air from canner; air pockets reduce temperature at a given pressure)
- Close vent; allow pressure to build to required level
- Begin timing when target pressure is reached
- Maintain steady pressure for the full processing time
- Turn off heat; allow canner to depressurize naturally (20-45 minutes depending on size)
- Open vent/petcock; wait 10 minutes before removing lid
- Remove jars with jar lifter; cool undisturbed for 12-24 hours
Processing Pressures and Altitude
Standard pressure for most vegetables is 10 lb with a weighted gauge or 11 lb with a dial gauge at altitudes below 1,000 feet. At higher altitudes, water boils at lower temperatures, so higher pressure is required to achieve the same internal temperature:
| Altitude | Weighted gauge | Dial gauge |
|---|---|---|
| 0-1,000 ft | 10 lb | 11 lb |
| 1,001-2,000 ft | 15 lb | 11 lb |
| 2,001-4,000 ft | 15 lb | 12 lb |
| 4,001-6,000 ft | 15 lb | 13 lb |
| 6,001-8,000 ft | 15 lb | 14 lb |
Processing Times (Selected)
All times are for pint jars at altitudes below 1,000 ft:
| Food | Time |
|---|---|
| Green and wax beans | 20 min |
| Beets | 30 min |
| Carrots | 25 min |
| Corn (whole kernel) | 55 min |
| Potatoes (cubed) | 35 min |
| Tomatoes (crushed, acidified) | 15 min |
Quart jars require longer processing times; consult the NCHFP tables. Using pint times for quarts is a safety error.
All processing times and procedures should be verified against current NCHFP guidance (nchfp.uga.edu) before canning. Older cookbooks, family recipes, and non-USDA sources may contain outdated processing times that do not meet current safety standards.