I was looking at the label on a can of Italian roma tomatoes (similar to San Marzano) and I noticed an ingredient called an 'acidity controller'.
This makes perfect sense to me, but it doesn't go as far as to say what that ingredient consists of. It seems like it might fall under the same ambiguity as 'herbs and spices' as far as requirements to list ingredients. Baking soda-ish things immediately come to mind, but does anyone have a more factual grasp of what's commonly used to control acidity in canned tomatoes?
Most varieties are actually quite tart out of the tin, which is why I was a little surprised to see that they use anything at all. Is it just something they use to lower the acidity enough in the event that the can is dented and the barrier stopping the tomatoes from actually interacting with the metal damaged?