We have premade our tomato sauces (spagetti, chili, etc) before, then canned it. We also can the "water" that cooks off the tomatoes when you are cooking them down to can the sauce. If you add cabbage to it while they are cooking down then it will add vitamins to the "water" and it makes great vegatable broth for soups later in the winter. I can't use alot of tomatoes due to the acid (and hubby can't eat raw tomatoes, he's alergic) so the broth works great to add taste and alot less acid.