The acid ingredients used in salsa help preserve it and prevent botulism poisoning. You must add acid to canned salsas because the ingredients’ natural acidity may not be high enough. Commonly used acids in home canning are vinegar and lemon juice. Lemon juice is more acidic than vinegar, but has less effect on flavor. Use only vinegar that is at least 5% acid and use only bottled lemon juice.
The exact weight of tomatoes will depend on the variety you use. I like to use roma (paste tomatoes) if I have them because the water content is less but any kind of tomato will work. The key is to peel the tomatoes and let them drain. See the step-by-step tutorial below the recipe for a visual. I like to pull out and discard the thicker white core of the tomatoes.
I just made this wonderful salsa a couple of days ago with roma tomatoes. I 4X the recipe and ended up with 32 pints of salsa. We liked it so very much I am thinking of doing more with the 1 1/2 bushels of regular tomatoes that I have. Do you think that the regular tomatoes would have too much liquid in them or would the draining take care of that problem? I didn’t add the paste last time so I would probably add it for sure to make it thicker.