For me, it all started last year around March. I was preparing for Tigress’s March Can Jam focusing on alliums, and was dying to can some caramelized onion jam. I must have read damn near ten canning cookbooks, and not one had an onion jam recipe. And with no tested, from a cookbook recipe to base my recipe off of, I had to resort to making a delicious onion relish.
During the process, I learned that onions are a low-acid food and require a high amount of acid to be able to can with a water bath canner. This means it is trickier than usual to create a water bath onion jam recipe, because all of the ones I found were for pressure canning (and I don’t own a pressure cooker). Tigress even warned us that onions were prime subjects for botulism. Seeing that I was also seven months pregnant at the time and slower than a pig in molasses, I gave up on my water bath onion jam search.
Cut to the beginning of August. I finally coming out of my “I had a baby” fog and wanted to can something delicious, so I went back to the Tigress Can Jam March round-up, and found this onion jam recipe by Rebecca of Market Life SF blog. It looked delicious, and in my rush to can the recipe, my baby-addled brain completely forgot about the great onion jam search of ’11. I tweaked the recipe to my liking and canned away! I forgot until I tried to post the recipe on Punk Domestics, and Sean kindly pointed out that my acid might be off.
I’m not a big fan of botulism, so I first contacted Rebecca from Market Life SF to find out where she got her original jam recipe (a Martha Stewart magazine). I assume Martha tests her canning recipes, but I wanted to be sure. I read up on the subject of water bath canning a non-pickled onion product. This Doris and Jilly Cook post was a great refresher on the debate, and inspired me to want to test the pH of my recipe. After some more research (which I did in between feeding and entertaining a crying baby because I’m a rock star), I discovered that pH strips, which Doris and Jilly suggest using, are only safe for food products with a pH of 4.0 or less. I was fairly certain my onion jam would be slightly over 4.0, so I would need a pH meter to properly test it. Hot damn, it took a lot of work to get to this point!
More photos, and tips on selecting a meter and using it test your canned foods after the jump.