Basics of pressure canning foods
How to pressure can foods correctly so they stay safe for consumption.
Pressure canning is the only safe method of preserving low-acid foods. Low-acid foods include vegetables, meats, fish, and poultry. Pressurized steam creates the needed temperature of 240 degrees Fahrenheit or higher that will destroy the bacterial spores naturally present in these foods. As the jars cool, a vacuum is formed, sealing the food in the jars and preventing any new microorganisms from entering and spoiling the food.
Michigan State University Extension recommends these steps for proper pressure canning:
- Put two to three inches of hot water in the pressure canner. Place filled jars on the rack in canner and secure lid as directed by canner manufacturer.
- Leave vent port off, turn heat to highest setting and heat canner until steam flows from the vent port.
- Once steam pours steadily from the vent, let it escape for 10 minutes to drive air out of canner.
- Place weight on vent port and allow canner to raise to the proper pressure.
- Start counting processing times once the dial gauge or weighted gauge has reached the recommended pressure (see manufacturer’s directions).
- Regulate heat to maintain steady pressure. If reading decreases from the recommended pressure, bring pressure back up and start timing process again.
- When timed processing is complete, turn off heat and wait until canner returns to zero on a dial gauge and 30 to 45 minutes for weighted gauge (see manufacturer’s directions).
- Remove jars with a jar lifter and place on a towel or cooling rack.
- Leave jars on the counter, undisturbed for 12 to 24 hours.
- After cooling, check that all lids have properly sealed.
- If a jar has not sealed, the contents can be reprocessed according to recipe directions or the jar must be refrigerated and eaten immediately.
MSU Extension offer pressure canning dial gauge testing. It is recommended each year to have dial gauge pressure canners calibrated for safe food preservation. Pressure canners with weighted gauges do not need to be tested.
For further information on pressure canning and other food preservation methods visit MSU Extension Online Home Food Preservation.