Headspace in jars

Asked September 6, 2014, 11:18 AM EDT

I can tomatoes from my garden. With all i've read about the variance of acid in the tomatoes I've gone with a pressure canner to minimize the possible issues with that factor in canning. What I've found on 2 of my batches is after processing my jars have more headspace than intended and I can't find a well referenced answer to tell me if this is an issue. The recipe called for 1" of headspace and several jars now appear 1 1/2" I have checked the seals and there appears no issue with a good seal on the lid. Can you advise if the excess headspace means this batch can't be put up? thankyou

Washington County Oregon home food preservation

1 Response

As long as the jars are sealed they will be safe. When the jars end up with more head space it is usually a sign that the jar siphoned some of the liquid during the processing. This happens for a number of reasons. In the pressure canner, jars were filled too full, pressure fluctuated during the processing, jars tilted when taken out of canner, etc. Raw pack will tend to siphon more that hot pack because when the air cooks out of the tomatoes they tend to rise to the top of the jar taking liquid with them.

As for the safety. It doesn't matter whether you using the boiling water canner or pressure canner. The internal temperature of the jar is the same. You will tend to get less siphoning with water bath canning.

Because of the variation in pH for tomatoes it is recommended that we add 1 T bottled lemon juice per pint or 2 for quarts. This will assure you a safe product regardless of the method of processing or variety of tomato. .

If you have other questions you might like to call the OSU Food Preservation/Safety Hotline 1-800-354-7319. Certified Master Food Preservers are available to a personally answer your calls M-F form 9 a.m. - 4 p.m.

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Nellie Oehler

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