Canning is one of my favourite methods for preserving foods. But not everything is suitable to be canned using the traditional water bath method. Water bath canning restricts your preservation options to acidic foods. So unless you water to make a jam, jelly or pickle out of your chosen food, you’re out of luck. That’s where pressure canning comes in to save the day.
On our homestead, we aren’t fortunate enough to have a cold storage or root cellar. Therefore, I’m constantly searching for other ways to preserve our harvest. Since Hubby and myself don’t want to be eating pickles all winter as our sole food source, pressure canning allows us to preserve non acidic foods safely.
Why Pressure Canning?
The purpose of any canning method is to remove oxygen to prevent spoilage, and to kill any bacteria that may already be present. Many bacteria are killed by acidity and heat, which means water bath canning is simply removing the oxygen from the jars, and Bob’s your uncle. Acidic foods are considered foods that have a pH of less than 4.6. (On a scale of 1-8. 1-4.6 being acidic, 4.6-8 being neutral or alkaline.) The acidity of these foods is what kills bacteria. Vinegar is, obviously acidic, which is why pickling is so effective. But so are many vegetables.(like certain varieties of tomatoes, and oddly, strawberries, which have a pH of 3.5)
For non acidic foods, like meat, broth, legumes, and vegetables stored in water, very high temperatures are needed to kill all bacteria. Especially bacteria like botulism, which can be deadly. Water boils at 212F but the temperatures needed to kill all bacteria can range as high as 240-250F. Those high temperatures can only be accomplished through pressure canning. The tightly sealed lid causes steam pressure to build up inside the pot and allows the temperature to rise much higher than normal boiling water. The other part of the process is time. To allow the high heat to penetrate through the food in the jars, different amounts of time are required. (More time for quart jars, than for pint or half pint jars.)
It’s very important therefore that recipes are followed that are approved by an official source. All pressure canning specific cookbooks have been approved by these sources. Companies like Ball Canning provide quite a few of these recipes. And when you buy a pressure canner, most will come with a recipe book that includes correct pressures and time for many foods. Untested recipes can sometimes be too dense for the temperatures to penetrate fully, and certain things like dairy have not been tested enough to give conclusive results.
Types of Pressure Canners:
There are two main types of pressure canners. One is a Dial Gauge canner and the other is a Weighted Gauge canner. On a Dial Gauge canner there is a dial on the lid that indicates with a needle how many pounds of pressure have built up inside the pot. On a Weighted Gauge canner, there are a series of differently weighted pieces that can be placed over one of the vents and will wobble at specific rates. You can adjust the amount of pressure in both of these types by slightly adjusting the temperature that your stove is set to. I prefer the dial gauge canner, because I like being able to see the accuracy of the pressure.
WARNING: Pressure Cookers are NOT Pressure Canners. Though they both build up pressure under their lids and can accomplish high temperatures pressure cookers are not accurate enough. Pressure canners have been built and calibrated to accurately reach and hold high temperatures. And they are much more delicate pieces of equipment. With a pressure cooker, you would not be able to be certain of the temperature inside and therefore can’t be sure your food is being processed safely.
At higher altitudes water boils at a lower temperature and gases expand more. So it’s important to check your altitude (a simple google search of your location can tell you this) and to adjust your pressure accordingly. Processing times remain the same. Below is a table showing different pressure adjustments for different altitudes.
|Feet above Sea Level||Dial Gauge Canner||Weighted Gauge Canner|
Foods That Can be Pressure Canned:
- Stone fruits
- Beans/Lentils in water
- Vegetables in water (peas, carrots, potatoes, etc.)
- Soups, Stews, Chilis
- Tomatoes & Sauces. Some varieties of tomato linger in the pH range of 4.6-5.0, so it’s better to be safe than sorry.
All foods that can be water bath canned can of course be pressure canned as well. If you are having a big canning day and don’t want to switch methods, you can do it all in the pressure canner.
- Pressure Canner
- Rings and new Lids
- Headspace Measuring Tool
- These are super important to make sure that jars seal correctly and don’t overflow or burst in the process. They’re also super cheap, like this one.
- Jar Funnel
- Magnetic Lid Grabber
- Jar Grabber
- Rubber or Waterproof oven mitts (Not mandatory, but helpful)
- Slotted spoon (depending on what you’re canning)
- Dish Towels
- Cutting Board
- White Vinegar
Parts of a Pressure Canner:
When you’re learning pressure canning the lid of your canner is the most important part to familiarize yourself with. The big pot is a big pot, there’s a small can rack inside, and the lid twists and seals onto the pot. All that is pretty basic. On the lid though, is where all the important information is held. The lid will have some or all of these parts and it will vary a bit depending on brand.
Overpressure Plug: This little rubber plug is a vent that will lift slightly and open during the process to allow for excess pressure to be released.
Vent/Cover Lock: This little vent is also a lock for the lid. The lids on pressure canners close pretty tightly but this little piece will only pop up when the pressure inside the pot has built up. Once pressure has built up and caused it to pop up, it’s no longer safe to try to open the lid, and as a bonus it will actually prevent you from being able to open the lid easily.
Dial Gauge: Only present on dial gauge canners. This is very straight forward, it is a dial that indicates the pounds per square inch of pressure inside the pot.
Vent Pipe: This pipe is the main vent for allowing steam out of the pot. The vent pipe will be important when starting up the process. You’ll need to watch the steam coming out of it to know when to add the jiggler.
Weighted Gauge (Jiggler): On a weighted canner, these will come in a number of sizes with different weights corresponding to them. On a dial gauge canner, this piece acts as a secondary pressure gauge. It will begin to rock back and forth or jiggle, if the pressure gets too high.
Pressure Canning Process:
Gather Equipment & Food
As with anything, begin by gathering all your equipment. Make sure everything is clean, and your work space isn’t cluttered. Also make sure you have a good couple of hours, as canners need to be monitored throughout the process.
There are 2 main forms of processing your food. You can use the hot packing method or the cold packing method. Very simply, hot packing means filling your jars with something cooked, like stock, soup, or stew. And cold packing is when you fill your jars with something raw like vegetables or meat. Prepare your foods according your recipe. For this example I’m canning some duck stock using the method from the Presto Canner Recipe Book. Check out my post about making stock here, and get your own stock canned up!
Sterilize Jars & Lids
Start by sterilizing your jars, lids, and rings. Heat your oven to 350F, and lay your jars on their side directly on the racks of your oven for about 10 minutes.
Put your new lids (don’t reuse old lids as they won’t seal properly) and rings (rings can be reused) into a bowl and cover with very hot water. Lay a dish towel on top of a cutting board to protect your counter and keep your jars from sliding. Pour some white vinegar into another bowl and have a clean lint free towel ready beside it.
Place the canner on the stove, on a burner that is as close to the same size as possible. Pour in about 3 quarts of water, or up to the lowest indicated line inside your canner. Add the jar rack to the pot and turn the burner on to medium high to begin warming the water. Warming the water here isn’t mandatory, but I find it speeds up the pressurization later.
Prep the Food & Fill the Jars
For this process I’m using the hot packing method. The stock has been brought up to a boil. Remove your jars from the oven using your jar grabber and place them onto the dish towel lined cutting board. Put the jar funnel into the first jar, and ladle in the hot stock, leaving 1” of headspace. Remove the funnel, use your magnetic lid grabber to retrieve a lid from the hot water.
Place the lid on the jar, followed by a ring, and tighten it just to secure. Don’t over tighten the ring, or the jar may burst. Use your jar grabber to transfer the jar to the canner. Repeat the process with the remaining jars.
Once all the jars are full and in the canner, align the arrows on the lid with arrows on the pot, and twist the lid on. You may need to press them together slightly, as there is a gasket in the lid to create a tight seal. Remove the jiggler, raise the heat of the element to just over medium, and allow the pressure to build inside the pot.
Vent the Canner & Begin Building Pressure
I leave my stove set at just over medium for this venting step. Watch the vent pipe closely until you can see a steady stream of steam coming out of it (this takes mine about 5-7 minutes). The cover lock will sputter and then pop up during this time. Once you see a steady stream of steam coming out of the vent pipe, start a timer for 10 minutes. This allows the pot to completely fill with steam.
After ten minutes, very carefully, drop the jiggler onto the vent pipe, and lower the stove temperature to medium low. Now pressure will begin to build inside the pot. My canner is a dial gauge, so for the next 15-18 minutes the dial will start to rise. If it’s rise very quickly I lower the temperature slightly.
For pint jars of stock, the pressure must be at 11. Once the gauge reaches 11, I lower the stove temperature again, to 2.5 on my stove(the simmer setting). If the pressure goes higher than 11 that’s okay, but make sure it doesn’t stay too high, for too long. Once the pressure is at 11, set a timer for 20 minutes for pints and 25 minutes for quarts. Monitor the pressure throughout to make sure it doesn’t drop below 11. If it does stop your timer, get the pressure back up and start the timer again.
Gently Lower Pressure
When the timer does off, turn off the heat, and very, very gently, lift the canner off the heat. Don’t open it, or remove the jiggler. Allow the pressure to drop slowly on it’s own, which can take another 15-20 minutes. Once the cover lock has dropped, you can remove the jiggler, but allow the canner to sit for another 10 minutes or so.
Next, still very gently, twist the lid to the open position, but don’t remove it. Allow the canner to sit like this for 30 minutes to an hour. This might all seem like overkill, but if the pressure or temperature changes too fast, your jars can overflow or burst. Taking your time at this stage is critical.
Let Your Jar Relax
After all the waiting and cooling, you can now remove the lid, tilting it away from you so steam doesn’t burn your face. Remove the jars from the canner with your grabber and let them stand undisturbed for 12-24hrs at room temperature. The jars can then be stored somewhere cool and dark (like a basement) for months.
Pressure canning takes time and care, but it means you can truly preserve as much of your harvest as possible without the need for a root cellar. I have completely fallen in love with this process. My favourite things that I canned this year have been stock and potatoes. On busy work days, it’s awesome to simply grab a jar of stock without having to thaw it, and cook up a high quality soup, stew or sauce. Or quickly fry up some potatoes.
I really hope you give this process a try, and if you do, let me know how it goes! And Happy Canning!