Wednesday, October 20, 2010

The importance of using a pressure canner

In the comments section of my last post on the canning closet, someone asked about how folks canned low-acid foods in the past without a pressure canner.  My guess is, they didn't.  Or if they did, they faced the very real possibility of poisoning themselves with botulism because of improperly canned food.

I decided to address this issue in a separate post rather than burying my answer in the comments section, because it's so important.

If you're interested in learning to can, please remember this: NEVER EVER EVER CAN LOW-ACID FOODS WITHOUT A PRESSURE CANNER.  Boiling-bath methods DO NOT KILL THE MICRO-ORGANISMS in low-acid foods.  I'm serious about this, folks.

Some people swear that their grannies never used a pressure canner and only used a boiling-bath to can meats, veggies, etc.  Well, granny must have been blamed lucky she didn't kill her family using that technique.

A small anecdote: early on in my canning days, shortly after my husband and I got married, I decided to can up a favorite dish of mine: chicken in homemade barbecue sauce. I followed all the steps and canned two 18-pint batches (my canner holds 18 pints at a time) for a total of 36 jars.

I was so proud of myself! Here were all these gleaming jars of chicken and BBQ sauce. I didn't need to refrigerate them - I could store them on a shelf at room temperature. It was a novel and wonderful concept.

It's worth noting that in those days I stored my jars with the rings still on because I naively thought the rings were necessary to keep the lids tight. They're not, of course.

A week late I decided to open a jar and have the contents for lunch. When I looked at the shelf that had my canned chicken on it, I gave a cry of dismay.

Every lid - every single lid on my 36 jars of chicken in BBQ sauce - was bulging. I had evidently done something wrong.  The lids hadn't sealed properly and the food was contaminated. Since the jars had rings on, the lids couldn't pop off - but they would have if the rings weren't holding the lids in place.

It broke my heart, but I threw out the contents of all those jars. It also taught me an important lessons: pressure requirements and processing times are in place for a reason. Shortly thereafter I bought my beloved canning bible, Putting Food By, and have seldom had a failure since.

I taught myself to use a pressure canner simply by following the directions that came with the canner.  Anyone can teach themselves to can simply by following directions and not skipping any of the safety steps.  Alternately, your local County Extension Service usually has classes or at least individuals who can teach you to use a pressure canner.

There's nothing mysterious about using a pressure canner, it's just a matter of keeping an eye on the pressure gauge (I highly recommend a kitchen timer to clip to your collar so you'll remember to check the pressure every five minutes or so).

But whatever you do, do NOT think you can escape using a pressure canner if you're serious about preserving foods.  All meats, vegetables, and most sauces, etc., are low-acid and need to be pressure canned.

A reader pointed out a distinction I should address: a pressure CANNER is not the same thing as a pressure COOKER.  I've never used a pressure cooker so I can't speak with authority on those, but I do know they're not the same thing and cannot be used interchangeably.  A canner has a gauge which gives you the accurate buildup of pressure in the canner.  Not sure about what gizmos a pressure cooker has.

I'll try to answer questions about canning in the comments to this post, but please don't try to convince me (or worse, any novice canners reading this) that boiling-bath methods are safe for low-acid foods - because THAT IS INCORRECT.

Okay, taking a deep breath and stepping off my soap box....


  1. Another great post Patrice, thank you! I'm pretty new to the pressure canning world and can totaly relate to your chicken story, I did the same thing but is was to fifty ears of beautiful sweet white corn.

    I ten learned that pressure canning was required and ran out and purchased myself a pressure COOKER, not canner by mistake. I think it is also important to point out that an actual pressure gauge is required to safely pressure can, because as you mentioned different foods require different amounts of pressure. Altitude also has an effect and must be taken into account when pressure canning at elevation.

  2. I just found a pressure canner at a thrift store, I'll be taking it to the extension office soon to get the gauge checked and I just ordered a copy of the 'Putting Food By' book. While freezing food is quick, it isn't reliable during a power outage. I'm looking forward to a well stocked pantry!

  3. Thank you, Patrice! I've had my own botches of canning before too, including eating something that I thought I had improperly canned, and thank goodness I turned out to be wrong! The only thing I'd ever heard about canning going wrong was a brief lesson in a biology class I took in college. I'm happy to know better now.

  4. I had my pressure canner for over a year before I got up the nerve to use it the first time last fall.

    So far, I've canned chow chow relish, apple butter, chicken and chicken broth. As I type, I'm waiting for batch number one of potatoes (like you, I get the leftovers from our local food bank and SCORED in potatoes this month!) to de-pressurize so I can put batch number two in.

    I've my fingers crossed, because I've not canned potatoes before.

    You are my inspiration, thanks for the blog!


  5. Great post! I'm assuming that the chicken BBQ was hot water bathed?

    Just a couple comments...Grannie may have hot water bathed low acid foods by boiling, and boiling and boiling them. And she might have been lucky. My Grannie told me a story about she and Grandpa doing just that with corn, and then storing it under their bed (the only place in their 1 bedroom cabin). About 6 weeks later, the lids started popping. They fed the mess to the pig....and the pig died. True story.

    As for the pressure canner vs. pressure cooker, the rule is, you can use a pressure canner to cook, but not the other way around. Pressure canning requires a gage, as one of your readers correctly noted, and pressure cooking does not. Most pressure cookers, do not have a gage. But canners are dual purpose.

    For example, you could pressure cook old roosters in that big All American easily. The meat would fall off the bone, and they would be done in about an hour.

  6. Thank you for writing about pressure canners; just last week I thought about asking you why you use one. I bought the book you use, but I haven't actually opened it yet. About throwing away your chicken, last year my daughter brought home a lovely quart jar of chicken soup from a friend's mom. I set it on the shelf thinking I'd heat it up for lunch soon. About a week later I noticed the pantry didn't smell very good and there was liquid all around that jar. The chicken soup had spoiled; when I opened the lid bubbles were rising to the surface. Only then did I realize that the mom had just used the jar to store the soup, it wasn't canned. The lesson I learned: if you put something in a canning jar, be sure the person knows if it's actually been canned or needs to be refridgerated and eaten!

  7. I'm not trying to convince anyone not to use a pressure canner. In fact, i have a brand new All American in my kitchen, that i am planning to try out tomorrow when i can some chicken stock.

    However, my granny and my aunts (who are still living and will testify to all this) most certainly did can quite a bit of meat with a water bath. I'm not saying they should have or that that was the best thing to do, but they did it, they raised families doing it, and we're all still living and thriving. So there is something to it.

  8. Hey Patrice,

    Thanks for always having such great posts. I did want to tell you that I recently purchased a Presto Pressure Canner and Cooker...(mainly because you and Enola are always inspiring me) It's all one in the same. It comes with a pressure dial gauge and a pressure regulator. I've only used it for putting up peaches in a water bath so far but, I look forward to pressure canning soon. Your canning closet looks awesome, by the way. Mine is much smaller but, I'm workin on it!

  9. I learned by ruining 14 quarts of beans.

    A pressure canner is simply a pressure cooker that is big enough to hold jars. Properly equipped, both have a pressure gauge, an emergency relief plug, and a weighted steam relief. I recently pressure cooked a big piece of deer meat in my 17 quart canner, then cut it up and canned it in the same vessel. Came out very good.

    I recommend the All American brand, made by Wisconsin Aluminum Foundry. The have metal to metal seals, and required no gasket. A torn gasket will render a pressure vessel useless and they may be hard to come by someday.

  10. in the olden days when a pressure "canner" was hard to come by due to expense etc...canning was done with water bath for high acid foods..and then for low acid foods a canning "steamer" was used...also, more salt and vinegar was used as well...and then of course there is the "drying" method too. i have used all of these methods, with some success and some failures. i have a pressure "cooker" which i use almost as much as i use a microwave-some of the best pot roast comes from pressure cooking. then i have two large pressure canners-which if you have a really lot of stuff to can two canners are just as easy to use as one...gets a lot done in half the time...(like if you have bushels of stuff that gotta be canned quickly you can do your food prep one day and then the sterilizing and canning the next day.) because you followed directions you should have one rule in place for consumption...always put freshly canned goods on a shelf and leave it alone for at least two weeks-you will know by then if it was a success or not and you don't have to taste it to know it. i have a neighbor who still dries her fruit between two screens set on the sunny porch and on her shed roof...that is where i draw the line and don't cross!

  11. I have an actual Presto Pressure Canner that does not have a gauge on it, just the "jiggler". So all of them do not have gauges.
    Also my small pressure cooker from Presto has directions on how to can pints in it. Have done it quite a few times when I didn't have enough to get the big canner out.
    have you ever canned any pork other than bacon?
    Love the posts! Happy Canning! Ann from KY

  12. Wonderful advice.

    I just started canning myself and have been overly cautious. I use a Presto 23qt pressure caner. I didn't know what to buy so I bought the biggest one I could find. I jumped right in by canning bacon and hamburger. I did this about 6 weeks ago and all is still good with my lids.

    I also just ordered Putting Food By and wow! what a difference in the amount of information. I was solely working from the Ball canning book and what I had seen on your blog and Enola's.

    I am still gaining confidence in what I have canned because it is new to me.

    But the thought of being able to can the meat in my freezer and not worry about power outages is great! And being able to make jams and jellies out of the left over fruit is really awesome.

    I guess what I am trying to say is I'm already addicted.

    And by the way Patrice the re-canned store bought relish and pickles turned out very well. Thank you for the advise.

  13. I have one book of the Foxfire series of books written in the late '60's about the old timers in the Appalachian region. College students were attempting to preserve some of the country wisdom that was being lost. In the interviews with the old folks I noticed they reported that they cooked everything for hours. If my memory serves me correctly, botulism is killed by boiling after 15-20 minutes. Therefore although their food WAS improperly canned, it all worked out in the end because they cooked everything so long. I agree with you though-do it right the first time! I just thought I'd share an idea of why they were able to get away with it.

    1. Botulism is NOT killed by boiling after 15-20 minutes. Only molds, yeast and enzymes are destroyed at temperatures below 212 degrees F (boiling). But bacteria (such as Clostridium botulinum) produces a spore that makes a poisonous toxin--that's what causes bosulism. And this spore is NOT destroyed at boiling temperatures, no matter how long it boils. ALL low-acid foods must be processed at 240 degrees F, which can only be achieved with a pressure canner. You have been misinformed if you have been led to believe otherwise.

    2. Anyone who thinks low-acid foods can be safely preserved with boiling water bath simply by boiling it for hours has been misinformed. Boiling will kill molds, yeast and enzymes, but boiling does not kill bacteria such as Clostridium botulinum, which produced a spore that makes a poisonous toxin (botulism). This spore is NOT destroyed at the boiling point, and in addition, the bacteria thrive on low acid foods in the absence of air--which is precisely the conditions that exist in a sealed canning jar containing low acid foods. The only safe method of canning low acid foods is with a pressure canner, because bacteria must be processed at 240 degrees F, which cannot be achieved with a boiling water bath canner even it boils for a year!

  14. This topic is a public service. Thank you for sharing this valuable information.

    I haven't canned anything for several years, not since my mother passed away. She never used a pressure canner, but she canned many things with the water bath method. Meat, fish, and fowl were smoked or jerked, never canned in her family. I'm not sure why, but I think it was a matter of "better safe than sorry." Too many explosions and improper seals which led to wasted food, and in those days they couldn't afford to waste anything so they just didn't take the chance.

    This topic is a very valuable and important lesson and I applaud Patrice for taking the time to explain the basics of the process. Major kudos to you, Patrice.

    Anoymous Patriot

  15. Patrice, thanks for the post! A lot of good info here, especially for the beginner, but good reminders for us all. I have to agree with tick and disagree with you on the canner vs. cooker issue, though. using the proper weight on a pressure cooker to maintain the temperature has the same effect as maintaining pressure in a canner. The difference in terminology is the size, mostly. As you stated, the trick is to maintain the proper pressure (and therefore the proper temperature, based on water at saturation conditions) for the prescribed time to ensure safety. You can do that in a cooker, a canner, or a homemade device, as long as the conditions are met.
    Thanks again for this post and all the rest; I'm learning every day!

  16. I purchased a pressure canner last year on clearance. I have since stocked up on jars, lids, rings, and more jars all on clearance....

    Every now and then, I get into a panic that I purchased a COOKER and not CANNER and run to look ;)

    It is a canner and since finding your site, feel prepared enough to pull that bad boy out and give it a shot.

    Thanks :)

  17. To Ann, from Kentucky--
    Can roast pork. It's wonderful. I chunk it up into fist sized pieces, brown it on the grill, and stuff jars moderately full. (Do not fully cook the meat, just brown it good.) Fill the jar half full of broth, chicken will do nicely if you don't have pork. You don't need to fill the jar to the standard 1/2 inch from top because the half-done meat will provide the rest.
    When ready to use, it makes wonderful Hot Pork Sandwiches with mashed potatoes. Just thicken the broth with flour or cornstarch.

  18. I now have the pressure cooker that I bought for my mother well before her passing. I've been a bit paranoid of using it since I didn't get the instructions with it. I don't want to get exploded don't you know? At any rate now I recently got upper dentures so I figure if I'm ever gonna' eat chicken gizzards again, I'd best be learning how.

  19. Amen! My grandma apparently water bath canned green beans and my neighbor does juice using the inversion method. Sigh. Drives me bonkers. I'm too... ahem, picky to do anything besides straight up water bath or pressure can (or freeze).

  20. Am late to this topic but wanted to mention that after buying a Presto pressure COOKER I called Presto about why it could not be used as a canner and was told it had to do with the size: Safety testing of low-acid pressure canning at that time had not been done on pots 16-quart or smaller and there is a concern that a smaller pot will not bring the entire jar contents up to the required temperature to kill the botulism spores (250 degrees). Since its safety has not been confirmed by adequate testing, they don't want it used that way.

    I see 16-quart sizes advertised on Amazon now as pressure cooker/canners so maybe the testing has been done, but I would still call the manufacturer before buying to see what they say.

  21. That should be 6 quarts or smaller is a cooker. any thing over is a canner. There are 10qt, 12qt, and 15qt canner's too. In general the most popular is the 21qt or 22qt depending on the manufacturer. As a Master Food Preserver we were given these HUGE books as our guide lines. This book is now available on line at this link.