If you're like me, you had a grandmother [or neighbor] that was always canning something-and also always seemed to have it handy whenever they needed it for a recipe, even out of season. With the gardening bug that bit many during COVID, maybe YOU have some extra tomatoes that you want to preserve for later. Food52 has you covered with great tips for canning tomatoes.
While using your bounty of tomatoes (whether you grew them or purchased them), is an incredible gift, especially during long, cold winter months, there are a few things about canning them you should know.
1). It is really important to use bottled lemon juice not fresh, because the bottled lemon juice is guaranteed to be at 5% acidity, which is the minimum you should use for safety purposes. With fresh lemons, the PH can be all over the board -and that can be problematic. You can also use either distilled vinegar or citric acid.
2). Before processing the tomatoes, screw the ring on the jar gently until it comes to a natural stop. At that point, give it 1/4 turn more and absolutely no more. If you go any further, there will be no way for the natural expansion in the jar as it is processing, and you risk the jar blowing out at the bottom.
3). Once you've processed your tomatoes, let them sit in the water bath for 5 minutes more before moving them -it helps to make sure the lids are sealed.
4). Leave the rings on the jar and do NOT check for 'doneness' (pushing down on the lid to see if it has sucked down) for 24 hours. Waiting 24 hours, allows the lids to really, set. Also, if you take the rings off before the 24 hours is up, you risk losing the seal.
5). By no later than the third day (though after the initial 24 hours) take the rings off and store the jars in a cool, dark place. Storing them with the rings off, allows you to know if there is an issue with the seal because the jars are 'leaking'.