DEAR PEGGY: In addition to allergies to gluten, I also have other food allergies that are sometimes awkward to work around. For example, I am also allergic to tomatoes. For recipes that call for only a slight amount of a tomato product, such as a tablespoon of tomato paste in a stew or 1/4 cup ketchup in a meat loaf, will leaving them out make a big difference in the final product, or would I need to add/increase an ingredient of a similar consistency? — M. P., New Hartford, NY
For most applications where tomato products are used in a small amount, you can just omit the tomato product without replacing it.
In the case of tomato paste added to a soup or stew, it's typically added to impart a richer flavor since it is so concentrated.
For meat loaf, if it's 1/4 cup ketchup, you might need to decrease the dry component(s) like the oats, cracker crumbs, bread crumbs, etc. I would add less dry ingredient(s) then, as you are mixing, add more gradually to get to the consistency you are used to.