Pressure canning is something I always wanted to try, but like a lot of people, I must admit I felt a little nervous about it. Upon reflection, I realized that most of it was just fear of the unknown more than an actual fear of pressure canning. If you've acquired a pressure canner and are a little apprehensive about trying, one helpful thing I did was to read the manual that came with my canner several times cover-to-cover which really helped me internalize the process and boost my feeling of confidence. I have a 16-quart Presto pressure canner that I love and have used many times now.
Of course, blog posts about pressure canning abound, many of which mention the initial newbie nervousness and how that (just like water-bath canning) if you follow the correct procedures there's no cause for concern. And, having put my faith in the good folks at Presto and now having successfully pressure canned many batches, I can assure you it's true! It just takes a bit of practice and getting used to, but it's actually quite easy and nothing to fear.
Of course, blog posts about pressure canning abound, many of which mention the initial newbie nervousness and how that (just like water-bath canning) if you follow the correct procedures there's no cause for concern. And, having put my faith in the good folks at Presto and now having successfully pressure canned many batches, I can assure you it's true! It just takes a bit of practice and getting used to, but it's actually quite easy and nothing to fear.
The Presto manual very wisely suggests doing a trial run with only water and no jars in the canner so you can see and hear how the canner works before actually committing yourself to a canning project. So, in preparation for pressure canning my very first batch (chicken bone broth) while the broth drained and cooled, I did exactly that and took my canner for a trial spin.
After washing the canner and its lid with warm, soapy water to remove any manufacturing lubrication, the manual suggests putting 4 cups of water in the bottom of the canner. There are measuring marks on the inside of the canner (they're not visible in the above photo) and the bottom mark is 3 quarts, which is the standard amount of water to use when actually canning jars of food. However, for this test run, 4 cups is all that is needed since we won't be running the canner for very long.
This is the underside of the lid held over the canner to show the ridges and valleys around the edge that interlock with one another when the lid is properly attached. Note, too, the metal tab sticking inwards from the edge of the canner near the bottom of the above photo. There is a pressure lock built into the lid (actually it's directly opposite the black circular rubber plug you see in the lid above and not shown in the photo -- must work on my "mindful photography" skills! -- I will be updating this page soon with better text and photos) that engages with this metal tab when there is pressure inside the canner. Essentially, what happens is the pressure lifts the pressure lock, pressing it against the metal tab and preventing the lid from flying off accidentally. The pressure lock also lifts above the top of the lid, so it's another visual indicator that the canner is pressurized.
When the arrow on the lid is aligned with the arrow on the canner handle, the ridges on the edge of the lid align with the valleys on the edge of the canner and vice versa. The lid can be pressed gently down into place.
The lid is rotated clockwise to align the lid handle with the canner handle, meshing the ridges and valleys and locking the lid onto the canner. The manual suggests using a fairly high heat, but to be careful of using the correct sized hob on a natural gas cooktop so as not to use one that is too hot which can potentially warp the bottom of the canner. So, I'm using the second-largest hob on my cooktop just to be safe.
Once the canner has heated and the water inside is boiling, steam will collect and raise the pressure, which raises the pressure lock. In the photo above, you can see the pressure lock lifted. The lock has also engaged with the metal tab on the inside edge of the canner as shown a few photos back, which acts as an additional safety latch. Note that there is not enough pressure to register on the dial gauge. This is because air is still being vented via the steam vent to the right of the gauge. Once there is a steady flow of steam coming out of the vent, the canner is left to vent for 10 minutes before the regulator is put on.
The regulator is a weighted cap that sits loosely over the vent allowing pressure to build inside the canner. Once the pressure has reached a high enough level, the regulator will start to rock back and forth, letting out pressurized steam in small bursts. This keeps the pressure inside the canner at a constant level. You can also help regulate the pressure by adjusting the level of heat under the canner and the Presto manual suggests starting at a relatively high level of heat and then lowering it slightly as the needle on the gauge approaches the desired pressure level.
Oddly, the regulator that ships with the Presto canner is a one-piece solid 15-pound weight. Many pressure canning recipes call for a 10-pound weight with 11 pounds on the gauge. This produces an internal temperature of 240ºF, which is enough to kill off the Clostridium botulinum bacteria, whose spores are responsible for botulism, among many other nasty bugs. Canning at 15 pounds of pressure would work (and is necessary for some recipes), but for a recipe that calls for 10 pounds, it's overkill and a waste of energy. Fortunately, Presto also sells an adjustable regulator that can be set for 5, 10 or 15 pounds. This is available for purchase separately and is well worth the $25 or so. However, why Presto doesn't just include this adjustable regulator with all its canners and forget about the solid 15-pound one is beyond me.
Here you can see the gauge is just past 10 pounds. I have the regulator set at 10 pounds and it is starting to dance, however it doesn't really show in the photo above. The needle of the gauge topped out at 12 pounds and I was successful in dropping it back to 11 pounds and holding it there by turning down the heat slightly.
Satisfied that I now knew the sights and sounds of my pressure canner, I switched off the heat and left it to cool and de-pressurize naturally on its own. It took about 10 minutes for the pressure lock button to drop and another 10 minutes for the gauge to return to zero. I took off the regulator at this point and I left the canner another 10 minutes after that before carefully opening the lid (pointing it away from myself to avoid any lingering steam).
Full disclosure: I am a complete wuss and while the canner was heating and especially after it started venting steam, I stayed at the other end of the kitchen, sometimes even hiding out in the living room having all sorts of "Omygoditsgonnablow!!" thoughts. It didn't, of course, not even close, and now that I know that it's just the canner's normal behaviour, I am fine with it.
So, now that I was comfortable with the pressure canner, I prepared to can my batch of chicken bone broth. When water-bath canning, it's easy and convenient to just sterilize the jars in the canner while it is heating. You can do the same thing with a pressure canner without the lid on, although the jars won't be completely covered with boiling water like they are in a water-bath canner and I find that the method doesn't lend itself easily. You need the requisite 3 quarts of water with a splash of white vinegar in the canner to complete the canning process and it's difficult to gauge how much water you should start with so that you end up with 3 quarts left after 10 minutes of a full rolling boil to sterilize the jars first. I could have got the water-bath canner out, filled it with water and boiled the jars anyway (big waste of gas if I wasn't actually going to can something in it!), or I could have run the jars through the dishwasher (I had just emptied it, didn't have enough jars to make a full load and it would take too long, so I nixed that idea, too). I decided the quickest, easiest and cheapest way was to sterilize the jars in my oven. 250ºF for 10 minutes and done!
The broth recipe states that it yields 4 quarts, so I put in an additional pint jar just in case I had some left over. The five jars and their rings fit perfectly in my small roasting pan! I put the jars into a cold oven so they could heat gradually and then counted 10 minutes once the oven reached 250º. Meanwhile, I placed 5 snap lids into a small saucepan, covered them with about an inch of water and started it simmering to soften the sealing gum on the lids.
After 10 minutes, the jars were ready so I quickly set the pressure canner up again making sure to add the full 3 quarts of water this time as this was a real canning session, not a trial run. The water I added was hot from the tap so that the hot jars would not be shocked and I added a splash of vinegar to prevent mineral deposits, same as for water-bath canning.
One by one, I filled a hot jar with hot broth, leaving 1" headspace (necessary to allow the proper boiling of the broth inside the jar), wiped the jar rim, centered the lid on the jar and applied the band, firmly tightening it and placing the jar into the canner. Unlike water-bath canning, you should tighten the bands on jars to be pressure-canned past finger-tight to prevent the contents from being siphoned out under pressure. The pressure inside the canner can be enough to loosen the lids sometimes if they are not properly tightened. Still, there's no need to go overboard -- tightening just until firmly snug will suffice.
Turn the heat under the canner on high and bring to boiling. When there is good steady stream of steam issuing from the vent and the pressure lock is engaged, start counting 10 minutes to vent the canner. After 10 minutes, cover the vent with a 10-pound regulator, and bring the canner up to pressure. When the regulator starts rocking, adjust the heat to hold the gauge at 11 pounds and start counting 25 minutes for quarts or 20 minutes for pints. If you have a mix of sizes, time for the largest size. In this case, I am canning quarts, so I will time for 25 minutes.
At the end of 25 minutes, turn off the heat and allow the canner to cool and de-pressurize naturally before taking the lid off. Always lift the lid away from you in case there is still some hot steam left in the canner.
I left the canner for about an hour before I opened it. I noticed the jars were still boiling quite vigorously, so in a brief moment of panic, I put the lid back on the canner and ran to find the manual. It stated that this is completely normal and some jars will continue to bubble for some time after being removed from the canner. The jars are not going to explode, nor are the seals compromised. The same as water-bath canning: if the lid "pings" and is solid, the jar is sealed.
All four of my jars eventually "pinged", although it did take one of them nearly an hour to do so. I must say it was a little disconcerting to see the jars sitting on the counter, bubbling away after so much time out of the canner. The bubbles did slow down and ultimately stop, but it took several hours.
The pictures and text describe my very first pressure canning session. I have since done many more and now I find it easiest to run the canner in the evening during or after dinner, then leave it overnight to cool and de-pressurize before opening it the next day and removing the jars to a folded tea towel on the kitchen counter. I have found that many jars actually "ping" and seal inside the canner while it is still processing and that's fine. All that really matters is that you have a good solid seal.
Press down on the center of each lid. If it feels solid and does not move, the jar has sealed. If it bounces or moves it did not seal. As a secondary check, remove the ring and, grasping the edges of the lid with your fingertips, gently lift the jar an inch or so up off the tea towel. If the lid stays on and feels solid, the jar is sealed. If the lid pops off, then obviously it didn't seal.
Jars that did not seal may be re-processed in the pressure canner again, but fresh lids must be used. A lid that has been used will most likely not seal again. Prepare the pressure canner with a fresh 3 quarts of water, a splash of white vinger, soften some new lids in hot water and re-process as above starting from the point where you just filled the jars.
Alternately, unsealed jars may be refrigerated and used with a week or so.
Sealed jars are shelf stable and should be stored away from light and heat. Cupboards, closets, basements are all excellent choices. Jars are at their best up to a year after canning, but do last much longer, however taste and colour will begin to fade over time.
