Pressure canning buttery caramelized onions. Safe?

I found a recipe for caramelized onions (6lbs of onions. 2 sticks butter. Crock pot cooking for 10 hrs. then preserve in pressure canner at 10psi for 70 minutes.) It sounded perfect for our onion-loving family, but now I am worried.

It made only 3 pints. One of which did not seal. And all three of which lost about an inch of head space. I now have second thoughts about storing these other two. I don't like the looks of the layer of solidified butter at the top. This was my first time using a pressure canner so am doubly nervous, though I am confident that I followed the processing directions. My questions are as follows: 1. Is it safe to store the ones that sealed properly for future consumption. 2. Is it safe to eat the unprocessed one this week 2. Is it safe to reprocess the unsealed one after it sitting out for 24 hrs. 3. Is it advisable to process only one pint jar in the pressure canner?



ukimmeru April 29, 2012
Thanks to you both. I had read some where that one shouldn't can dairy products, after I used these two sticks of butter, of course :) I will definitely discard the unsealed one at this point. It has been sitting out at room temperature for over 24 hours now.

And thank you for the helpful FAQ link. :)
ATL April 29, 2012
While I think the preceding was sound advice, I I want to add that I used to do some canning and a lot of jam and preserves-making. My motto has always been that when I have any doubt I throw it out. Or freeze, or refrigerate and eat within a brief period of time. When I was learning how to make jam, I was studying an older edition of The Joy of Cooking and came across this memorable line: "The home canner must operate at all times with a clear conscience." I loved this, and it has worked for me many times when I have been dubious about food safety.
sfmiller April 29, 2012
Assuming the recipe is from a reliable source, you followed it exactly, and the pressure gauge on your canner is accurate, the sealed jars should be safe for room-temperature storage. The extra inch of headspace isn't a big issue, as long as you have a good seal.

The rule of thumb is that reprocessing unsealed jars of canned food is safe if done within 24 hours. If it were me, I wouldn't bother for one jar--just store in the fridge and use within a week or so, or freeze it.

Here's a good home-canning FAQ:
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