How to Use A Pressure Canner Safely
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Canning and preserving food goes hand-in-hand with homesteading and self-sufficiency. And for the most part, it’s pretty safe and straight-forward.
Whether you’re water bath canning pickles, jams, jellies and fruits, dehydrating, fermenting or freezing, all of these methods are pretty easy and unintimidating for even the most inexperienced homesteaders.
As long as you follow tested recipes and proper procedures, there’s very little chance of anything going wrong during or after the preserving process.
But pressure canning can seem like a whole different ball game.
The pros & cons of pressure canning
There are a lot of pros to pressure canning. Once you learn how to use a pressure canner safely, the sky’s the limit when it comes to what you can preserve: Vegetables, meat, seafood, combination meals like soups and sauces, bone broth… Pressure canning opens a whole new world of possibilities when it comes to what you’re able to safely can at home.
But pressure canning also evokes fear in lot of people, to the point where many never bother to try it. And it’s not hard to understand why….
Is pressure canning dangerous?
Pressure canning has got a bad rap for being dangerous and even fatal. Stories of pressure canners exploding in the kitchen or improperly canned food killing people with botulism have scared many people off from ever trying pressure canning at home themselves. And I, admittedly, was one of these people for a long time.
But I knew I had to overcome the fear once and for all if I was ever gonna level-up my homesteading (and meal prep) game, and I just so happen to have a hand-me-down Mirro pressure canner that I inherited so I really had no excuse not to be pressure canning.
Last year I finally gave it a go. I pressure canned green beans for the first time. And ya know what? I didn’t die. And in fact the whole process was very anti-climactic (except for the part when I hid around the corner as it started rattling, just in case it blew up).
I had the chance to experience first-hand just how non-threatening pressure canning could be. And in the end I had half a dozen pints of homegrown, home-canned green beans that were safe to sit on the shelf until I was ready to add them to home-cooked meals. But there was still the dreaded threat of botulism to contend with. And with a one-year-old baby at home, I was still apprehensive to actually eat the beans I canned.
After doing extensive research, I felt assured that my beans posed no danger. Because as long as you follow the rules and a tested recipe, your home-canned food will be perfectly safe.
In fact, in 100% of the cases I found in my research, botulism from home-canned food was either caused by water bath canning a food that should have been pressure canned, or by not following the instructions and pulling food out of a pressure canner too early.
If you simply follow the steps in a tested pressure canning recipe, your food will be safe to eat.
Alright, I felt confident at this point that my green beans would be safe, so I opened up a jar and added them to some macaroni and cheese for my daughter and I to enjoy.
And we didn’t die!
How to safely pressure can foods at home
I decided to give pressure canning a go again this year. This time I canned up some pumpkin, and even though I remembered pressure canning being a rather pleasant experience last year, I was still a little nervous to try it again. Maybe I just had beginner’s luck?
I made sure to read and re-read every step before I began, and I even did a test run to check everything was working correctly (which it was). Again, when the gauge began to rattle I stepped back and peeked around the corner into the kitchen, just in case;) But again, nothing happened, and the whole process was pretty uneventful. Whew!
At last it was time to just go for it. So I chopped up a pie pumpkin and set to work preparing it for the canner.
I read and re-read all the steps once more and finally it was time to put the pumpkin in the jars and process them. I readied my jars, filled them up, measuring out a perfect one-inch of headspace at the top of each one, and then I placed them in the pressure canner with a few quarts of water, locked down the lid and let the canner heat up enough to start steaming.
Finally, after letting the canner vent for 10 minutes, I placed the weighted gauge on top and got it rattling, adjusting the temperature as needed until the rattling slowed to a few times per minute.
And then I waited. I tidied the kitchen and started writing my post about pressure canning pumpkin as the canner gently rattled away. After the better part of an hour it was time to turn off the heat, depressurize it and remove the jars from the canner to let them cool on my counter-top.
It worked, again! And I got all giddy about the beauty of home-canned jars of organic pumpkin lining my countertop. Because I’m a geek like that (and I’m guessing maybe you are too if you’re here right now;)
I haven’t had a chance to eat any of the pumpkin yet as I’m saving it for when pumpkins are out of season (hence why I canned pumpkin to be enjoyed later in the year), but I feel confident that it’s safe knowing that I followed a tested recipe and didn’t skimp on any of the steps. And in the end, that really takes the fear out of pressure canning. Because there’s truly no reason to be scared of it, as long as you play by the rules:)
The rules of pressure canning
So, what are the rules of pressure canning?
Here are some simple rules for pressure canning safely at home:
- All low-acid foods MUST be pressure canned, not water bath canned. Low-acid foods include red meat, seafood, poultry, vegetables, mushrooms and tomatoes, (although there are water bath canning recipes for tomatoes that use the addition of lemon juice to bring the acidity up to safe levels). So basically if it’s an animal or a vegetable, you gotta pressure can it. If it’s only fruit (ie. apples, berries, cherries, peaches, grapes, etc.) or is pickled in vinegar, it’s most likely safe to water bath can.
- You must use a pressure CANNER, not a pressure cooker, for at-home pressure canning. You can use a pressure cooker/canner, but never a pressure cooker on its own. Your pressure canner must have a pressure gauge on it and not simply a valve like many pressure cookers have. And no, you can’t pressure can in an Instant Pot. Maybe someday, but not today.
- Familiarize yourself with your particular make and model of pressure canner. This is one of those rare situations where you want to actually read your owner’s manual. Familiarize yourself with your canner and how it operates. Find out exactly how much water you should add to your particular size of canner and how to lock it and operate it properly. If, like me, you have an old hand-me-down canner and don’t have a copy of the owner’s manual, you can Google your make and model and find the manual online. Make sure older canners have all of their parts and replace any old or damaged pieces, especially broken locking mechanisms or gaskets.
- Always follow a tested, up-to-date recipe and don’t skimp on any of the steps. Canning is a science, not a creative endeavour. While you can get more creative as your understanding of the science of canning evolves, always start by learning the basics first. Don’t be a rebel (or lazy) when it comes to doing things by the book in this case. Your personal health and safety and that of your loved ones isn’t worth the risk.
- Breathe. You’ve got this.
I also recommend doing a test run to get comfortable with using your canner before you’ve got a batch of something inside. Bring it up to temperature and get comfortable using it and adjusting the heat to get a nice, rhythmic rattle going with your gauge.
Learn how long to wait to properly depressurize your canner before removing the gauge and unlocking the lid. And of course, always use oven mitts when canner is hot and open your canner lid away from you so you don’t steam-burn your face.
Parts of a pressure canner
It’s useful to know the parts of your pressure canner and their function too…
Gasket: This is the rubber ring that sits between the lid and the canner and seals it.
Vent Pipe: This is the vent where the steam escapes from. The weighted gauge sits on top of this during processing.
Overpressure Plug: This is a last-ditch safety mechanism that prevents the canner from exploding if it does build up too much pressure. The plug will pop out and let the extra steam escape.
Weighted Gauge: This is the gauge that sits on top of your vent pipe during processing. It has 3 holes corresponding to 5, 10 and 15 lbs. If your recipe calls for you to process your food at 10 lbs. of pressure, you place the 10 lb. hole over the vent pipe and the weight will start jiggling when the pressure inside the canner reaches 10 lbs. of pressure.
Many newer canners have a dial gauge and/or a weighted gauge for more specific processing temperatures, although the standard pressures required for most recipes are still 5, 10 and 15 pounds.
Canning Rack: This sits on the bottom of your canner so your jars don’t directly touch the bottom of the canner. Same as a water bath canner.
* The locking mechanisms on my Mirro Pressure Canner are on the lid and lock into place when the handles slide inline with each other. (I would link to the one I use but it’s an old version and I can’t find it anymore… This Presto pressure canner is very similar, but since it’s newer it has a dial gauge too).
The locking mechanisms on the popular All-American Pressure Canner are wing nuts that you screw down to lock the lid on.
Canning tools I use and love
I have a few canning tools that I use all the time whether I’m pressure canning or water bath canning. The jar lifter, the funnel and the scoop are essentials in my eyes. The Ball Complete Book of Home Preserving is my go-to resource for safe home canning recipes (mine is actually “Bernardin” brand because I’m in Canada, but it’s the same book). Almost all of the canning recipes you’ll find on this site are safely adapted from recipes in this book.
The book has 400 canning recipes including pretty much everything you could possibly think to preserve in a jar. I highly recommend making the investment and getting yourself a good, reliable canning recipe book. Clearly I feel more than comfortable endorsing this one:)
Step-by-step pressure canning instructions
Okay, okay. Enough of the preamble. You’re ready to dive in and begin. Here’s the step-by-step process for pressure canning…
- Follow all of the rules outlined in the previous section. Get your canner out and ready to go, familiarize yourself with how it works. Double-check your owner’s manual to find out exactly how much water you need to add to it. Make sure you know what exactly you’re canning, and find a tested recipe from a source you trust. My personal go-to’s are the National Centre for Home Food Preservation and, of course, my canning bible: The Ball Complete Book of Home Food Preserving.
- Clean your jars and bands with hot soapy water. Keep your jars hot. The nice thing about pressure canning vs. water bath canning is that you don’t need to sterilize your jars when pressure canning. Just keep them hot so they don’t crack when you fill them with hot food. You can achieve this simply by filling them with hot water after washing and leaving them in the sink or by leaving them in a hot, steamy dishwasher after a clean cycle.
- Prepare your canner, if you haven’t already done so. Place the canner rack in the bottom and add your water. The general rule is that you should have 2-3 inches of water in your pressure canner, but I follow my owner’s manual to be sure, which tells me exactly how many quarts of water to add. (This makes it easy because you can simply use quart-sized Mason jars to measure out your water and fill your canner). Don’t turn the heat on just yet.
- Prepare the food you’re going to be canning. If you need to chop vegetables and cube meat, I recommend doing this before preparing your jars so that they don’t cool down in the time it takes you to do food prep. At this point you can cook or prepare your food according to the recipe and get it ready to be packed into jars.
- Add prepared food to jars, leaving the specified amount of headspace at the top. Generally you want to leave a generous one-inch of headspace at the top of your jars when pressure canning, but check your specific recipe to be sure.
- Remove air bubbles, wipe rims, place lids on top and screw down bands. Just as you would when water bath canning. Then place your jars in the canner.
- Put the lid on your pressure canner and fasten it shut. Turn heat on high and allow heat and pressure to build up. Don’t put your gauge on yet. First let it get hot enough that steam starts to vent out of the spout. Let it vent for 10 minutes.
- After 10 minutes of venting steam, put your weighted gauge on the spout at the weight of pressure specified in your recipe (usually 10 or 15 pounds of pressure, depending on how high above sea level you are). Tip: Use oven mitts to put your gauge on as steam can be very hot!
- Wait until your gauge starts rattling consistently and then set a timer for the amount of time the recipe calls for. Then turn heat down until your gauge stops rattling constantly and starts rattling on and off a few times per minute (usually around 3 or 4 times per minute). This is where you want to keep it for the duration of processing time. I find seeing my burner to somewhere around medium heat get my gauge rattling just the right number of times per minute.
- Once the clock has run out and the processing time is up, turn off the burner. Let your pressure canner cool completely on the burner until the pressure has been reduced to zero. If your canner has a dial gauge, it will help to tell you once the pressure has returned to zero. But never rely solely on the dial gauge. Always make sure the weighted gauge has stopped rattling completely before removing and use oven mitts to remove.
- Let canner vent until there is no steam coming from the canner spout. Then remove lid carefully (away from your face) and let jars sit in the canner for another 10 minutes.
- Remove jars from canner and let cool completely on a towel on the counter before storing.
And that’s it! You did it!!!
That wasn’t so scary, was it?
Pressure canning tips & tricks
It’s helpful to know how to properly care for your canner to get the longest life possible out of it. It’s also useful to know how to handle some common problems.
Caring for your pressure canner:
- Always dump water out of pressure canner after using and dry before storing
- Add a tablespoon of vinegar to the water in your pressure canner if you have hard water and want to prevent water stains on your canner and jars
- Replace parts regularly to keep everything in good, safe working order
- Check your owner’s manual for any specific maintenance tips for your make and model
Common pressure canning problems
1. Help! My pressure canner has cooled completely but I can’t get the lid off!
No worries. This usually happens because the gasket is old and needs some lubricant. It’s probably a sign that you should order a new gasket, but in the meantime, as long as you are sure your canner is totally cooled but the lid is still stuck, give the lid a few gentle taps with a hammer and try to loosen the lid again. You might need to repeat this several times or wait another few minutes and try again. Rub a little bit of olive oil over the gasket to help prevent this in the future.
2. Help! There are little air bubbles floating to the top of the jar after I pull my jars out of the canner. Does this mean the jars didn’t seal or that my food’s unsafe to eat?
Take a deep breath. I had a freakout about this and then did some research and talked to some very trusted canning sources who assured me there is nothing abnormal or dangerous about this, and now I’m assuring you:) It’s actually pretty common for air to still be releasing after you’ve finished processing your jars. They could even bubble for up to an hour or two. There’s no need to be concerned unless it’s been going on for days or something. Then it’s possible something your jars is fermenting or spoiling so best to toss it out.
3. Help! I noticed the headspace in my jars went down and/or I lost a lot of liquid out of my jars. Are they still safe to eat?
This is called siphoning, and it’s very common. As long as the jar is still at least half full with liquid and your lids sealed, your food is still safe to eat.
If you have any other canning questions, make sure to drop them in the comments section below!
Wishing you homemade, homegrown, homestead happiness 🙂
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I was about five minutes maybe ten shy of finishing a batch of chick peas and the flame blew out allowing pressure to drop before I saw it. I was able to quickly raise it back and processed an additional ten minutes. Is that okay?
While it *might* be okay, I wouldn’t recommend risking it. The official guidelines state that if the pressure drops you need to start the process over again from the beginning. Otherwise I would just pop the jars in the fridge and plan to eat soon. I know how frustrating this is as one of my burners went out last year in the middle of pressure canning a big batch of beef stew. I ended up freezing it all instead. Murphy’s law, right?!
Thank you for bringing out the safety of using a pressure canner. I’ve been using a pressure canner for years. My husband is a retired tool & die maker, he looked over the canner and from his way of looking at the pot it’s next to impossible to blow up. Unless you do what the “Boston bomber” did to modify a pressure canner. Under normal conditions and proper use it is very safe.
I got a all american old style canner, its new was never used by the previous owner, can someone explain how to use it?
Hi Beverly, I also have a glass top stove, should I forgot the idea of pressure canning????
my weighted gauge never jiggled? Why and also some of the lids expanded on the jars. Help first time using a mirro pressure canner. canning beans.
If the weight never jiggled then it could be that your pressure was too low or that your vent pipe was clogged, although if it were clogged then the pressure would have probably built up and popped out the overpressure plug. You can check the vent pipe by looking through it to see if you can see light through the other side. If not then clean it with a pipe cleaner.
My guess, though, is that the pressure was too low. What heat/temperature did you have it on? Also, what type of stove are you canning on? Most canners don’t work well on glass top stoves as the heat automatically switches off and back on again so they don’t maintain a consistent temperature. Also, some canners with a slightly concave bottom don’t sit flat on glass top stoves so this could be the reason.
I’ve never heard of lids expanding on jars. Could you explain in more detail? I would immediately store the beans in the fridge and use them soon. Don’t let them sit on the shelves for safety reasons or toss them. Better safe than sorry.