It Turns Out I Know A Lot About Canning

Do you ever have one of those moments where you’re like “holy crap I know a lot about this!” Well that happened to me a few weeks ago. My next door neighbor is going through her second trimester hardcore nesting stage and she discovered canning. She was taking me all sorts of questions and get this, I knew all the answers! Since I like to share here it is. For this post I’ll be mostly focused I think on the safety aspects of canning and sharing a link to my absolute favorite canning blog and recipe there in for vanilla pear jam! I made it this week because we literally can not be without it in the house. A few years ago I was really into it for a while but I’ve calmed down a lot since then. But writing this really makes me want to break out the pressure canner!


If you get into canning you’ll get a lot of advise from people that have been doing it for years, who swear by their method and have loads of experience and a lot of that is bad advice. Most of what I’m going to tell you is on the USDA guidelines but was delivered via food in jars. The thing is these guidelines have changed a lot over the years and so best safety practices have changed too. Yes that WAS the best practice to the time your grandmother canned but now we know better. Science works like that too and as a scientist I get that! Just pull a Paris Hilton and tell people what they want to here and do what you’re going to anyway, might she be a genius after all? Also some people be crazy and we’ll address that too. So here are the safety things you need to know to avoid giving botulism to your friends or family.

1.) Here comes the crazy, ready, putting your canned jars through any cycle in your dishwasher is not the same as processing in a hot water bath. Don’t do this, if you do you deserve the seizures.

2.) An instant pot is not a pressure canner, it says so on their site and the FDA data sheet, don’t believe me go look. For pressure canning a certain pressure must be maintained for a certain time. That also varies by how far you are from sea level and what you’re canning. Do you know exactly what pressure your instant pot gets to and for how long, yeah, neither do I!

3.) Squash can not be safely canned it’s too dense to reliably reach high internal temperatures. Not even with a pressure canner. Dice it and freeze it on sheets instead!

4.) Store your jars with the rings off on the shelf and on after you open them in the fridge. Id something is growing in there it will produce gas like CO2 and pop the lids off. It’s the easier way to know.

5.) Once your jars are cool test your seal by picking them up by the lid only, if you can it’s a good seal. I’ve picked up 2 liter jars of pickles and that sealed and stayed fine. If not no big deal just put the ring back on and store it in the fridge for immediate consumption.

6.) Don’t trust the pop! Jar lid dimpled in is not good enough. Read tip 5 again.

7.) So here is the deal with tomatoes. They must be pressure canned all the time officially. Whether it’s sauce, salsa, whole tomatoes or diced they are not acid enough to only use a water bath. The pH needs to be 4.6 or below to be safely canned with a hot water bath. Tomatoes are right on that line. If they are more ripe, depending on the species or the crop they might be too high. Officially they need to be pressure canned even if you add a little lemon juice or vinegar.

7.) There are two types of pressure canners the type with the rocking wight that you count the clicks to tell the pressure or the type with the gauge. I tend to thing the type with the gauge is safer as you can’t leave it. Not everyone shares this opinion though.

8.) Never reduce the amount of sugar, or vinegar and maybe salt from a recipe these are the preserving agent and reducing it could push it below the safe zone.

9.) Pectin has a pretty short shelf life. Check the expiration date and use it by then. So stocking up might not be the great idea it seems.

10.) Never think you can process and store a freezer jam (etc) recipe on the shelf. The reason it might be a freezer recipe is that it doesn’t contain enough preservatives to be shelf stable.

11.) When processing jars of multiple sizes process for the largest jar contained there in. If you’re worried about quality or crispness in smaller jars just take those out as their time comes due.

I took this picture of pickled eggs with a 3G back in the day, it was grainy so I made it black and white!

12.) You can re-use the jars as long as they don’t have a chip or crack, the rings as long as they are not dented but not the lids. They are only designed to seal safely once for sure. Maybe your mom did it you still shouldn’t. However keeps a few around marked used for transporting and storing other stuff.

13.) Label with contents, date AND the batch. That way if something goes wrong you can isolate and destroy the entire batch. Plus you’ll know how old they are and what it is. Sharpie on the lid works great since you can only use them once.

14.) Use modern recipes published since the year 2000 at least before that they might contain older dangerous instructions.

15.) Use the right jars. As pretty as the vintage ones with glass lids are they are not considered safe for canning. Use these for fridge only preserves or storage.

Finally if in doubt throw it out, and check the rest of the batch!

I get that you might hear other things from people with literally decades of canning experience. The thing is best practices change over time. Just look at how the best treatments in medicine have evolved over time. Because there is a chance you could make yourself really sick it’s worth knowing and staying up on the most up to date information on the subject. Also make sure any recipes you’re following from the internet are from trusted sources. If every other strawberry jam recipe has a 1:1 sugar to berry ratio and you find one that is 1:3 ask yourself “is that safe?” What’s the craziest piece of canning advice you’ve ever heard?

2 thoughts on “It Turns Out I Know A Lot About Canning

Add yours

  1. I’ll take that on board, thanks. 🙂 I’ve never used a pressure canner before, just stored my jams, chutney, etc in hot jars that have been “cooked” in the oven first, then sealed with the “popping” lids.


    1. Technically… we shouldn’t be processing in the oven anymore a boiling water bath is considered safer. It’s because any bacteria on the outside is more likely to be killed by boiling water then just heat alone. Check your seals by picking them up with the lid only and consider storing them with the rings off. But you already read that. Have fun canning!

      Liked by 1 person

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