Elizabeth Adams
September 29, 2015

Follow these safety guidelines for pressure canning.  

melissa b./Flickr

With the boiling water-bath canning method, the tools and rules are straightforward. The food preserver gathers high-acidity vegetables, such as tomatoes, berries or peaches, prepares the food to their liking—perhaps with some added acidity—fills the jars, and, within a few minutes of processing, removes the jars to cool.

But for those canning junkies who want to spread their creative wings and stock a diverse collection of foods in their pantries, salsa and strawberry jam lose their appeal after a few rounds. At some point, the serious food preservers recognize the necessity of a pressure canner—the only piece of kitchen equipment permitting cooks to preserve low-acidity foods at home. The pressure canner provides a gateway to new canning recipes, enabling cooks to preserve homegrown vegetables, like green beans, carrots, beets and peppers (foods with a pH of 4.6 or less), and all without the step of pickling to strike the right pH balance. Pressure canners also allow you to preserve protein-rich foods, such as stocks, meats, soups and wet beans.

Before you get too eager to break the chains of your water-bath canner, it’s important to take into account the few risks and dangers that accompany pressure canning. It’s also essential to understand how pressure canners work before diving right into your first preservation project. Here are a few tips to make pressure canning a little less intimidating.

1. Know How Your Pressure Canner Works

When preserving with a pressure canner, food preservers end the risk of potentially deadly food poisoning by processing jars in a pressurized environment. When carried out properly, pressure canning guarantees protection from the growth of spores that cause botulism, a deadly toxic poison created by the presence of bacteria in foods. Spores responsible for botulism cannot survive heat of 240 degrees F or higher, so pressure canning removes the threat by reaching a high internal temperatures unattainable with the open boiling water method.

Before starting with your pressure-canning equipment, review the instructions for your specific model. Make sure all pieces of equipment, including canning jars and lids, are clean and free of cracks or nicks. Prepare food as directed by the recipe, allowing for the recommended headspace in the recipe of your choice. Place the rack in the canner and fill the canner with at least 2 to 3 inches of water or the amount of hot water specified in your recipe. If you’re using a hot pack method, heat the water up to 180 degrees F prior to pressurizing, and if you’re going the raw pack method, heat the water to 140 degrees F.

Using a safe lifter, place your readied jars into the canner one at a time, taking care not to spill. Your canner should be large enough to fit at least four quart jars. Fasten the lid securely, and then crank up the heat to the highest setting, being cognizant not to not overheat the canner. Leave the weight off the vent pipe or open the petcock, letting the steam flow for at least 10 minutes—time to safely vent the canner and ensure there’s no air left inside, which could jeopardize the process. After venting, place the gauge on the vent pipe or close the petcock. From this point, it will take three to 10 minutes for pressurization to occur.

2. Stick Around

During pressurization, you should stay close by to monitor signs of success or failure. You need to regulate the heat, adjusting slightly and only as necessary, to maintain a consistent gauge pressure, which should be specified in your recipe. One of your gauges will jiggle a certain number of times, and the other will rock steady, during this process—and these are both good signs if you own a newer model canner. Process for as long as indicated in the recipe and keep a kitchen watch handy to track the time.

Any time pressure drops below the recommended amount specified in your geographic altitude (usually between 10 and 11 pounds, depending on the type of canner), abandon the process and start over. Variations in pressure will result in a loss of liquid, or siphoning, and also result in under-processing. If you suspect at any time the pressure within the canner was compromised, turn off the heat and move the canner from the burner, lifting upward. Leave the canner alone until it cools naturally.

3. Allowing The Canner To Cool

Once you’ve met the correct amount of consistent pressure and time requirement for your recipe, it’s time to gradually allow the canner to depressurize. Turn off the heat and, if you must, lift—do not slide—the canner off the burner using caution. It’s also acceptable to leave the canner in place with the heat turned off. Even after the pressure gauge dials back to zero and the gauge is cool to the touch, leave the canner alone. No steam should escape when you lift the gauge. In newer model canners, vent locks will open when depressurization occurs. It’s a good idea to leave the canner alone overnight before releasing.

4. Purchase A Newer Model Canner

According to the National Center for Home Food Preservation, you should only purchase pressure canners manufactured after the 1970s. Older models are clunky and the vents were operated manually, but modern pressure canners include removable racks, automatic vents and cover locks, as well as a safety fuse. Modern canners will also come with a weighted gauge to regulate the pressure inside the canner. The gauge should jiggle or shake during pressurization, which is a mechanism for maintaining the right level of pressure. Older models do not include many of the new safety features, which include an automatic unlock function the moment of depressurization.

5. Seek Out Recipes—Or Someone With Experience

The validity and reliability of a tried-and-true canning recipe is the preserver’s greatest asset regardless of the method in practice. Seek out recipes from credible sources, not just Internet sources or your grandmother’s cookbook. In the past 50 years, canning technology has changed, and so have standards and guidelines for preserving food. Start with the Ball Complete Book of Home Preserving or visit the National Center for Home Food Processing for recipe ideas.

Even with a clear-cut recipe and a new pressure canner, you still might have apprehensions about using a pressure canner. To further ease your fears, consider partnering with a friend with experience using the equipment for an afternoon of canning from your garden. Or contact your local agriculture extension office, which often offer classes on canning methods.

About the Author: Elizabeth Adams is a freelance writer based in the Bluegrass region of Kentucky. In addition to gardening, cooking and homesteading, she loves riding horses, practicing yoga, and spending time with her French bulldog Linus and husband Shawn.

 


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