The pressure canner is a valuable tool in home food preservation as long as you take measures to ensure your equipment is in working order and you follow acceptable canning practices. When it comes to pressure canning, there are things we simply shouldn’t do because the risk of failure can be dramatic.
It’s all too easy to become complacent when you’ve been canning for decades, but Elizabeth Andress, PhD, professor at the University of Georgia and contributor to the National Center for Home Food Preservation website, sheds some insight on a few practices home canners should avoid to prevent disaster.
1. Skip checking over the canner.
Often we’re so eager to start canning that we forget to carefully inspect the pressure canner. General use, particularly if you can a lot, wears on the equipment causing potential failure. Inspect the rubber gasket and other parts to make sure everything is in good working order before you fill your first batch of jars.
“You also need to look through the vent ports to make sure there are no blockages,” Andress says. If your model contains a rubber safety plug, check that it fits well and is not cracked. If the safety plug is damaged, the canner might not reach full pressure.
Andress also recommends testing it by bringing an empty canner up to pressure before starting your canning session. This way, you don’t discover something is wrong after you’ve spent hours preparing your meat or vegetables for the canner.
If parts are failing or you’re having frequent issues with your canner, it might be time to look into a newer model.
“One of the advantages of the new canners are the safety features,” Andress notes. Buying a newer one ensures you’ll have a more reliable canner that won’t allow you to open the lid until the pressure is completely down.
2. Forget to have your gauge checked.
It happens to a lot of us: We harvest a massive amount of green beans that needs to be processed immediately and simply forget to have the dial gauge checked before the canning season. However, checking your pressure canner’s dial gauge is an important safety measure, as it might cause the canner to work incorrectly—or not at all—so take the gauge to your county extension office to ensure its accuracy.
Andress notes that dial gauges work through a contraction of metal and different heat settings and can become distorted or broken with use or if bumped. It’s terribly disappointing to have a canner full of food while the needle on your gauge remains still. In addition, the gauge accuracy can change over time, so an extension agent will tell you if you need to make adjustments in the pressure. If it’s off by more than 2 pounds, replace it.
“If you have the weighted gauges, make sure you really understand the parts needed,” Andress says.
Weighted gauges have rings used to indicate the proper pressure level in 5-, 10- and 15-pound increments. Know what you need before you begin canning. For example, if you need to maintain a pressure of 12 pounds, use the rings needed to reach 15 pounds, and have it ready before you start the canning session.
3. Not keeping your hot pack hot.
Canning is not a timed event, but food, particularly in the hot-pack method, needs to be canned and sealed as quickly as possible.
“Those processing times are based on a whole lot of factors,” Andress says, including a particular temperature of the hot-packed food. If you allow your hot-packed meat and vegetables to cool too much, it throws off the process and presents a safety hazard. “Thoroughly read every step of the process [before you begin],”
Sterilize the jars and keep them hot prior to packing, and have your lids at the ready. “Seal the jar quickly, and don’t let it cool,” she says.
4. Fail to vent the canner before starting the timer.
Once you load your canner, lock down the lid, but leave the vent pipe or petcock open. Venting brings the temperature up to the 240-degree-F mark before processing begins, which is critical for safe food preservation.
To vent, turn the burner on high heat and allow it to boil until you see steam coming out. Once there’s a strong, continuous jet of steam, set the timer for 10 minutes. (Some manufacturers have different recommendations on their models, but the USDA’s rule of thumb is 10 minutes.)
“That is extremely important to safety,” Andress says. “If you don’t get all of the air out of the canner, the steam doesn’t reach the proper temperature.”
5. Omit citric acid.
The standard recipe for canning tomatoes or tomato sauce calls for the addition of citric acid to increase the acidity level because many tomato varieties don’t have levels high enough to be considered safe. The temptation is to skip the additional acid because you’re using a method for low-acid foods.
Andress says there hasn’t been enough research completed to accurately give the time and pressure needed to process tomatoes or tomato sauce without the additional acid. Without the science to back it, the risk will be over-processing or under-processing, which can be detrimental to your health.
“You’re risking botulism, which is potentially fatal,” she notes. If the recipe says to add citric acid, add it!
6. Ignore the altitude adjustment.
“Water boils at a lower temperature at higher altitudes,” Andress says. “In a pressure canner, we can get the temperature higher by increasing the pressure and leaving the time the same.”
If your location is 1,000 feet above sea level or higher, reference the required pressure and processing time for your elevation. If you don’t, you’re risking not having sufficient heat to kill the botulism bacteria.
“A common misperception is that as long as the jar seals, it is safe even if they didn’t process long enough,” Andress says.
Using a pressure canner is a tremendous way to put up healthy food for your family, as long as these few guidelines are met. Make sure your canner is in good working order, and follow the instructions for each type of food you process. If you do, you’ll have a pantry filled with delicious meals ready at any time.