Ask the Goats: Bad Seals in the Pressure Canner

A note from the goats: This blog used to have a weekly feature called “Ask the Goats.” At the time, most of our readers were people we knew in real life, and we quickly ran out of questions. Since then, our audience has grown, and we’re now getting a steady stream of questions on Twitter, in the comments, and via e-mail. We’d like to use this forum to share our answers with the rest of you, who are quite likely wondering about the same things. Keep the questions coming, and we’ll try to answer them on Mondays!

Q: I’ve just read your instructions [for canning chicken stock]. I’ve tried twice now to can a batch of stock in my pressure canner and most of the jars won’t seal. I removed air bubbles, left 1″ in the jar, and followed the other instructions. Any ideas why these jars won’t seal?—Jen

A: After Jen asked me this, we had a long e-mail discussion about the various options. She was indeed doing everything right, but we eventually settled on two things. First, her stock was fairly fatty. While this makes for delicious stock, it can make getting a good seal more difficult if fat gets trapped between the lids and the jar. But secondly, and more importantly, this was a case of opening the pressure cooker lid too soon.

But what, exactly, constitutes “too soon”? Most pressure canning instructions, including mine, tell you to wait about 10 minutes after letting the pressure drop of its own accord before opening the lid. Over time, though, I’ve found that this is too soon. A pressure canner full of chicken stock is very, very hot. Even when the pressure drops inside the canner, the temperature and pressure inside the jars is still quite high. The dramatic change in pressure from removing the lid (even after the indicator has fallen) can be enough to cause liquid to spurt or seep out of the jars. This not only causes you to lose some of your precious chicken stock, but it also interferes with the seal. So now, whenever I pressure can anything with a significant amount of clear liquid (beets, tomatoes, stock, etc.), I always wait at least an hour after the pressure drops before opening the lid. Ideally, I do this at night and just turn off the heat and go to bed. The next morning, I take off the lid, and viola! Everything seals.

Jen e-mailed me about a week later with an update. Success!

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8 comments to Ask the Goats: Bad Seals in the Pressure Canner

  • Gosh, I have been having the same problem! Could be the fat–I don’t de-fat my stock. I do let the canner cool for a while, but I may try your trick of leaving it over night.

  • Daisy Mae

    Now I’ve always been taught not to let your stuff sit in the pressure canner overnight. Something about bacteria being able to grow in that nice warm moist environment and concern about when the jars actually sealed.

  • Becca Riley

    Daisy Mae, I was taught the same thing. But honestly think about it. If you keep the canner sealed nothing is going to get in or out of it, the heat and pressure already killed the bacteria that might have been in there before the processing. So that nice warm moist environment won’t grow any bacteria, it will just be a nice safe place to keep your canned goods until they are cool enough to ensure a good seal.

  • I’m so glad this question was answered! I just used my pressure canner for the first time, canning potatoes, and I had one jar not seal. I’ve NEVER had a jar not seal when water bath canning, so I was confused how a pressure canned jar didn’t seal. But I’m pretty sure it was because I took the lid off too soon. I’ll have to wait longer from now on. Thanks for the information!

  • Lu

    Yeah, I do 10 minute intervals. 10 minutes after the pressure drops to zero and the vent lock goes down, I remove the safety weight; 10 minutes later open the lid; and 10 minutes after that remove the jars.

  • Kristin

    I just had this same thing happen too. It’s my first time pressure canning anything. The broth spurted out when we took them out. They all sat on the counter overnight and two of the three jars still sealed…are they safe or should I start all over?

  • jessica

    We just canned some green sauce using tomatillos and quart jars as well as a pressure canner. The lids did not seal, but I can freeze them. My problem is, there is an amber colored around the inside of each jar, and we can’t figure out what it is. Do you know?

  • jessica

    My husband said that he added oil to the sauce, so that is what the amber ring is inside, and I imagine that the oil boiled over and wouldn’t allow the jars to seal. Live and learn.