I am canning for the first time -- marinara sauce for gifts. I have the Ball book for technique. However it assumes tomato recipes are being made with fresh tomatoes and I used canned tomatoes (good quality organic ones, of course).
The canning instructions call for adding 1T of 5% acid liquid (like bottled lemon juice or vinegar), per pint jar. This seems excessive since the canned tomatoes already are more acidic than fresh. I plan to put some 6% balsamic in each jar.