I feel like such an idiot … but a few weeks ago I made some tomato sauce from the Ball Blue Book and, like the overworked, overstressed woman I am, I forgot to add the lemon juice. Now I’m worried. I asked a friend who’s very knowledgeable on this topic what to do and she said to just pop them open, boil the sauce for 10-15 minutes and then re-process, this time not forgetting the lemon juice, the theory being that the vigorous boil will kill any nascent bacterial growth. I’m still not sure though … Does anyone else have any thoughts on the topic? Or should I just chuck my 4 quarts of tomatoey goodness? Thanks in advance.
I believe your friend’s advice is correct. The danger in not adding lemon juice comes from an environment that is not sufficiently acidic to prevent botulism spores from growing. In this environment, if there are spores present, they will grow and produce botulism toxin which can cause paralysis and death. Fortunately for you, while the spores are not killed at home canning temperatures, the toxin does break down completely.
So, if your canned goods have been growing botulism spores (and therefore toxin), reprocessing the tomato sauce will destroy any toxin that has been produced and adding the lemon juice will prevent the spores from growing again. If you are still nervous about the tomato sauce, just be sure to boil it for 10 min before serving.
As an added comfort, most tomatoes are acidic enough to prevent botulism spores from growing anyway; it is only some of the newer low-acid cultivars that are not. Here is what the CDC says about preventing botulism