Home Canning FAQs: What is Headspace?

Many canning recipes and directions refer to leaving "headspace in a jar"; usually around 1/2 inch; but what does this mean?


Headspace

The unfilled space above the food in a jar and below its lid is referred to as headspace. Directions for canning typically specify leaving 1/4-inch for jams and jellies, -inch for fruits and tomatoes to be processed in boiling water, and from 1- to 1-inches in low acid foods to be processed in a pressure canner.

This space is needed for expansion of food as jars are processed, and for forming vacuums in cooled jars. The extent of expansion is determined by the air content in the food and by the processing temperature. Air expands greatly when heated to high temperatures; the higher the temperature, the greater the expansion. Foods expand less than air when heated.  This is why you must leave more headspace when using a pressure canner!

Illustration of headspace.

 

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Canning books

Canning & Preserving for Dummies
by Karen Ward
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The Ball Blue Book of Preserving

This is THE book on canning!  My grandmother used this book when I was a child.  It tells you in simple instructions how to can almost anything; complete with recipes for jam, jellies, pickles, sauces, canning vegetables, meats, etc.  If it can be canned, this book likely tells you how! Click on the link below for more information and / or to buy (no obligation to buy)

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Home Canning Kits

This is the same type of  standard canner that my grandmother used to make everything from applesauce to jams and jellies to tomato and spaghetti sauce. This complete kit includes everything you need and lasts for years: the canner, jar rack, jar grabber tongs, lid lifting wand, a plastic funnel, labels, bubble freer, and the bible of canning, the Ball Blue Book. It's much cheaper than buying the items separately. You'll never need anything else except jars and lids (and the jars are reusable). To see more canners, of different styles, makes and prices, click here!
 

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