air space in home canned green beans

Asked July 10, 2019, 3:32 PM EDT

I pressure canned some green beans - successfully I think. However, some of the jars have air in the top now that they are canned and cooled. The jars sealed. I raw packed according to the directions in the Presto canning book and another book on canning that I read and filled with boiling water leaving 1 inch of head space, got out as much air as I could prior to processing. One processed jar has about a 1/2 in and another about 1.5 in of air in the top. Are these safe to store this way? Thank you

Carroll County Maryland home food preservation

1 Response

Hi Thank you for your question.
Reading about your jars before processing, did all jars have an inch of headspace (the space between the top of your product and the bottom of your flat lid)?

Were the metal screw band tightened until fingertip tight (when there is first resistance)? I wonder if you lost some liquid from your jars during the processing time because jars were not tightened in a way to prevent liquid escaping the jars during processing.

According to the National center for home food preservation and the varying headspace you encountered:
"Do I really need to leave a certain amount of headspace in the jar?

Yes, leaving the specified amount of headspace in a jar is important to assure a vacuum seal. If too little headspace is allowed the food may expand and bubble out when air is being forced out from under the lid during processing. The bubbling food may leave a deposit on the rim of the jar or the seal of the lid and prevent the jar from sealing properly. If too much headspace is allowed, the food at the top is likely to discolor. Also, the jar may not seal properly because there will not be enough processing time to drive all the air out of the jar." https://nchfp.uga.edu/questions/FAQ_canning.html#4

The way your jars processed may create a weak vacuum seal. You may want to use this canner load more quickly than keeping it shelf stable and opening later in the year.