6 Secrets of Hot Water Bath Canning You May Not Know

Expert Interview

We're canning, you're canning, just about everyone is canning these days. And we think that's pretty fantastic. But before you fill your kitchen with steaming hot glass jars and pounds of tomatoes, we have a few insider tips that might just make your next canning session go a lot more smoothly.
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Marisa McClellan of Food in Jars demonstrating apricot jam

A few weeks ago, I had the extremely happy privilege of attending one of Marisa McClellan's canning classes during the tour for her recently released book Food in Jars. (We featured Marisa here on The Kitchn during June with a series of guest posts on small batch canning.) She shared several canning tips during this two-hour class that I'd never heard before and cleared up a few mysteries. Let me tell you, there's nothing like learning from an expert!

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Use a measuring cup when filling jars to eliminate guesswork. (We forgot to put the rings on to keep the rims clean before filling these!)

1. Fill Jars with the Rings On - ...But, obviously, with the lids off, as in the top image. This keeps the rims clean while you're filling the jars and saves you the hassle of wiping them down later.

2. Use a Measuring Cup when Filling Jars - This just makes the whole process go more quickly and smoothly. If you're filling pint jars and using a 1-cup scoop, you know that two scoops will fill the jar. Easy-peasy. It takes away the guesswork.

3. Screw Lids Down "Fingertip Tight" - Screw the lids down just until you start to feel resistance when you tighten, aka "fingertip tight." Inevitably, some air bubbles get trapped inside the jars while you're filling them. If the lids are screwed down too tightly, those air bubbles don't have a way to escape during the hot water bath and can cause your lids to buckle. Leaving the rings and lids a little loose lets that oxygen escape without incident; the lids will form their seal as the jars cool.

4. Remove Rings Once Jars Have Sealed - Amazingly, you don't need the rings once the jars have sealed. The lids are so firmly sealed around the rim of the jar that you can literally lift them onto the air by the lid alone! Removing the unnecessary rings frees them up for other canning projects, avoids problems with the rings rusting during storage, and allows you to spot potential problems sooner — if the canned good is starting to ferment and create gas, the lids will pop right off.

5. The Bounce Test for Gauging Pectin - It's hard to know how much pectin a fruit contains, and therefore, how much you might need to add to get a jam to set properly. Here's where the bounce test comes in. Fruits that are high in natural pectin will have a more rigid cell structure and tend to bounce when you drop them onto a table, like blueberries and blackberries. Fruits that are lower in pectin tend to smoosh, like strawberries.

6. Label Jars with the Batch Number - Not only does this help keep your pantry organized, but if there's a problem — or unexpected success! — with one jar, you know which other jars you need to check. This is especially important if you're making multiple batches of the same fruit or vegetable over the course of the summer.

Are you canning this summer? What tips and tricks have you picked up from your canning experiences?

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Screw the lids on "fingertip tight" to allow air bubbles to escape during hot water bath processing

More Food In Jars
Small-Batch Canning Recipes from Marisa McClellan on The Kitchn
Visit Food in Jars, Marisa's blog
Find Food in Jars: Preserving in Small Batches Year-Round, Marisa' new book, at your local library, independent bookstore, or on Amazon.com

Related: How to Make Your Own Canning Equipment

(Images: Emma Christensen)

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