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I think that this is the part that most people panic about when it comes to safe home canning. Did my jars seal? Are they safe for my family to eat? How can I be sure?
Testing Jar Seals and Safe Home Canning Tips
The scary thing and that which is the worst problem that can come from canning (botulism) is unable to been seen or smelled. So what can we do about it?
First of all, and this is the biggest thing…make sure you follow the canning directions to the letter. You need to boil or cook your canned foods for the correct amount of time and the correct amount of pressure (if you are pressure canning). And be sure that during the time of cooking your canner stays up to the correct pressure (or keeps boiling if you are water bathing) for the entire time you are processing.
Who To Talk To About Safe Home Canning and Testing Jar Seals
You also want to make sure that you talk to your local extension office and find out if you need to make time/temp/pressure adjustments for your altitude. This is especially true if you are using a canning recipe from a website or something you are just unsure about.
If you aren’t familiar with your local extension office, you can locate one here: US Extension Offices. (By the way, if you didn’t already know, your extension office is a plethora of information on all things local, outdoors, growing food, etc. Utilize them!)
Once you have the basic pressure canning or water bath canning part down, you shouldn’t have much to worry about. But do you know how to test a seal on a jar properly? Here are some things to look for…
The most common method for testing jars is the Finger Test Method. Simply press on the middle of the jar lid with your finger. If the lid “pops” up and down with your finger when you press it, it’s not sealed and needs to be reprocessed. If it doesn’t move at all, it’s likely sealed.
Note: Don’t test canned foods until they are completely cooled and you’ve given them several hours to seal! Doing so might create a false seal and unsafe food.
All food should be reprocessed within 12 hours of the original processing. Anything longer than that and the food should be placed in your fridge and eaten up as soon as any other leftover food.
The next method you can try is the Spoon Test Method. Tap the lid with the bottom of a spoon. If it makes a dull sound, the lid is not sealed. If it makes a pinging noise, it is correctly sealed. Please note that if you did not leave headspace and food is touching the lid it will create a dull sound either way.
Of course, you can also look at the lid at eye level. If the lid looks flat or bulging, it’s not sealed. If the lid is nice and concave, it’s properly sealed!
Do not lift up the jar lid to test the seal. Doing so may break an otherwise good seal and allow bacteria to enter.
Do not remove a jar rim before the jar has cooled, but DO remove the rim before storing the jar. Re-tightening a rim after the jar is sealed can cause the seal to break.
Can you reprocess jars that don’t seal?
If your jar didn’t seal, don’t stress and get upset. It happens to the best of us! Even experienced canners who have been using safe home canning for decades have jars that don’t seal on occasion. It just happens. Here’s what to do if you have an unsealed jar or two.
Remove the lid and rim. Check the rim of the jar for any nicks or cracks. If you have a nick, discard the jar (or use it for dry food storage!) and place your prepared foods in a new, clean jar. Secure a new lid on the jar with a clean rim. (Do not reuse the lid you already processed the jar with.)
Reprocess the jar using the same process that you already used. It’s a good idea to leave some time in between your canning so that if unsealed jars do happen, you can add them to another batch instead of having just a single jar to re-can.
If you don’t want to re-process your un-sealed jar, you can always stick the food in the fridge or eat it for supper. Or you can freeze the contents for future use.
What do I do if my canning lids didn’t “pop”?
They may not always make the popping sound, so it’s not good to rely on that sound to know that the jar is sealed. Use one of the methods outlined above instead.
Are there foods that shouldn’t be reprocessed? (aka: What to do if my pickles don’t seal!)
Yes, but this is a quality issue and not a safety issue. Certain foods like pears can get very mushy if they are overly processed, and the end product will not be very good.
It’s better to put certain foods in the fridge and enjoy them now.
But my Grandma used to do it this way…
Yep, my Granny used to turn the jars over after making soup to can them with the heat from the food. (Not recommended!!)
We’ve learned much about food safety in the past several decades, and it’s important to go by what we know now. And yes, that includes canning tomatoes with some kind of acid. Tomato acidity has changed in the past 50 years and is no longer as high as it once was, putting tomatoes in the low-acid (or close to the low-acid) food category.
Safe Home Canning Websites
Here are some websites that you can also check to better understand the safety of home canning and preserving.
A Final Note on Safe Home Canning…
SO many people stress out about canning because of the risks, and I want to assure you that issues with canning, especially when directions are properly followed, are very minimal.
An average of 145 cases of botulism are reported in the US each year, and just 15% of those cases are foodborne (not even all from home canned goods!). Out of 327,445,198 US citizens, that percentage is an extremely small number. That’s about a 0.00000007% chance of contracting botulism from your food. (You have a better chance of winning the lottery!)
It doesn’t mean that we shouldn’t worry about it at all, but rather, not let it hinder us if we truly want to preserve food for our family. If you follow safe methods, the extra stress is not worth it.
Are you wondering what tools you need to get started canning? Watch my video below!
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How long have you been canning? Do you make sure to follow safe home canning methods?
Merissa has been blogging about and living the simple life since 2009 and has internationally published 2 books on the topic. You can read about Merissa’s journey from penniless to freedom on the About Page. You can send her a message any time from the Contact Page.
This article on Safe Home Canning was originally posted on Little House Living in July 2013. It has been updated as of September 2023.