In this episode, Kathy discusses headspace in canning and why it's important.
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Recipes mentioned in this podcast:
- Canning Tomatoes
- Apple Pie Filling
- Apricot Jam
- Canning Dried Beans
- Canning Fish
- Water Bath Canning
- Pressure Canning
In this episode you'll learn:
- What is headspace in canning
- Why headspace is important
- Why headspace varies depending on the contents you are canning
- How to measure headspace
- What happens if I leave too little or too much headspace
- Headspace in jars after processing
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Hello everyone and welcome back to Preserving the Pantry. Today we are going to be talking about canning again, and I really want to address some things about what I'm gonna call behind the scenes of canning. Today I'm going to talk about headspace in canning.
So headspace is defined as the space from the top of the contents in your jar to the top of the.
That's all it is, but it varies from recipe to recipe depending on what you're canning. So it usually varies anywhere from a quarter of an inch to one and one quarter of an inches. Sometimes you'll see a half inch, one inch, everything in there in between, and there's a reason for that.
Have you ever wondered, Well, when we are canning, whether it's water, bath, canning, or pressure canning, the contents in those jars are being heated to such a level that the air at the top of the jar in that head space is being forced out.
It raises it up just a tad, forces that air out. And then when you remove the jars from the canner, the lids depress and form a seal, and that head space at top doesn't have any air in it shouldn't have any air in it, and that helps preserve the food along with the temperature that you're heating it to.
So it really depends on the type of food that you are canning as to how much it's going to. As to how big of a head space you have. So when you usually have jams or jellies, it's a quarter of an inch. Some things, like my tomatoes that I have is a half inch space, so some things that you're canning, like beans, fish meats, apple pie filling, those are items that we're going to expand more in the job when they're in the jar, when they're being heated up.
And so they're going to have an inch to an inch and a quarter of headspace. So every recipe is going to vary on that. Some of the items, when they're being heated up, they naturally expand, and sometimes that's due to the amount of the air that's actually in the food.
So think about apples. They actually contain a lot of liquid, a lot of water, but they do contain a lot of air as well. And so those items expand and they'll take up more space. And so we need to have a little bit more of a head space on our jars.
So what happens if you don't have the right amount of headspace and you go ahead and fill it up and you just leave a quarter of an inch?
When you're supposed to leave an inch, what's going to happen? Well, a couple of different things can happen. First of all, if it has to expand and there's not enough room for those con that contents in the jar to expand, it's going to force the contents right out of the jar, and you're going to lose some of the contents, and that's okay as long as your jar still seals, but because it's going to be forcing the contents out, you run the risk of not getting a seal because you might have some of the sticky filling or part of the liquid that came through there, and it could cause the lid to not seal If you.
Underfill your jars, like if you're canning jam and you leave a full inch head space. Well, here's a couple things that can happen there.
First of all, you might not get all of the air out of the jar when it's canning, so you risk the possibility of the contents being spoiled over time, or you might have some discoloration on the top.
Another thing about Headspace is you only worry about Headspace before you process your jars. After your jars come out of the canner and they've cooled off and you're getting ready to put in your pantry, you might look at them and say, oh my gosh, there's no headspace left.
That's okay. The job is done, and hopefully you've left enough head space in there. It's one of the reasons though, that you're going to be removing the rings from the jars. Washing off the outside of your jars and then checking that seal and making sure that they're sealed, keeping that ring on, especially if your content's filled all the way up to the top, might show a false seal.
So you want to always remove those rings. Recipes from the National Center for Home Food Preservation should always indicate several things in the recipe, and one of those is the amount of headspace to leave. Another thing to that should be on there is the amount of processing time, how to process the size of jars, as well as how to adjust for your elevation.
One thing about headspace is sometimes I use the rings on the top of the jar as my guide for how, how much space I am actually leaving. That's a good guideline, but sometimes jars aren't always precise. So there are some tools that are out there you can put right on the rim of your jar, hangs over, touches the top of your contents, and you.
Get a real precise measure on your jars. Once you know your jars and you use the same type of jars, you can use those rings as a guideline, but make certain you know what those are. I hope that this was helpful and I hope the next time you can, that you understand a little bit more about Headspace. If you have some questions about canning, I'd love to hear what you'd like to know, know more about.
I'll see what I can find out. I'll research it and get back to you and post a new podcast. I'll see you next week in the pantry. Bye. Thanks for listen. And be sure to tune in again next week for more episodes of Preserving the Pantry.
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