jever, I am gonna read the link about Citric acid that Peter provided but for your personal preference why do you not want citric acid in your tomatoes? I am just curious what Citric acid does or does not do. But I will as noted read what Peter linked.
My brother in law is a salesman for GFS. He took me to a food show a few years ago where we tasetd different cans of crushed tomatoes. The 6-1 were the best tasting right out of the can. The rep said it was due to the lack of citric acid. The show was pretty informative. Since then I have tried a few different brands with and W/O citric acid and it always seemed like the brand W/O the acid was better.
*Edit* - I think citric acid gives off bitterness in the sauce. The crushed tomatoes with out added citric acid taste sweeter straight out of the can. IMO