What’s the deal with “Debubbling?”


November 28, 2023

Jars of home canned tomato sauce cooling on a wooden cutting board.

I had some grand plans to film some Instagram content this morning, do a chicken coop tour, all the goods – and then I woke up with not so much as a whisper of a voice. Love that for me.

So here we are. I wanted to quick address one of the most common questions I am seeing lately on some of my social media canning groups.

“I canned this and it has bubbles in it – but I debubbled it, is it okay?” “I forgot to debubble “product xyz”, do I need to throw this out?”

So let’s start at the beginning of the process. Beginner canning sets tend to come with this little plastic dull knife looking thing that they call a “debubbler”. Sometimes on the other end it will have some fairly handy stair steps to measure headspace. I can’t say I’ve ever owned one. A butter knife, chop stick, or kabob skewer does the same thing.

Why do I need to debubble?

Some products need to be debubbled, and others do not. For example I can’t say I’ve ever debubbled a jar of salsa. Or spaghetti sauce. But I always debubble my coleslaw and green beans. Why? The bubbles that you’re looking to remove from the jar are actually air pockets in the product. Something that more liquid products aren’t likely to have, but that may form in jars of vegetables or meat chunks. The issue is these air pockets will be removed from the jar during the canning process and if they are large, may leave you with less liquid in the jar than you need in the jar. Generally it’s not an issue if a little liquid is lost in the process, but too much can lead to product discoloration at best and the potential or spoilage at worse so it’s best to try and avoid the issue.

I Debubbled and they still came out with bubbles in the jar!

Okay, so this one is pure science. If you are water bath canning your jars are submerged in 212* boiling water. If you are pressure canning then the temperature inside the canner is much higher than that because of the additional pressure – with the additional pressure the water inside a pressure cooker will boil at around 250*.

Most “watery liquids” – think brines, syrups, and even tomato sauces – are also going to boil at 212* at normal pressure and 250* under 10-15# of pressure – aka, the inside of a pressure canner.

See where I’m going with this? Even if you’ve thoroughly debubbled a jar prior to placing it in the canner, the liquid inside the jar was boiling during the process. This high heat exposure is ultimately what renders the product inside shelf stable and safe to consume after many months or years on the shelf.

Fun fact: at extremely low pressure, .02atm to .03atm (1atm is the pressure at sea level) water will boil at room temperature. Remember that boiling is the conversion of a liquid to a gas – not the temperature of the water itself which will vary based on the surrounding pressure. I remember a science teacher in middle school throwing boiling water on use after it had been in a vacuum chamber at low pressure. It was only room temp but boy did we jump!

Happy Canning ya’ll!

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