Two popular books ("Dropping Acid" by Dr. Jamie Koufman and "The Acid Watcher Diet" by Dr. Jonathan Aviv) claim that Title 21 of the FDA regulations require that all low-acid foods be acidified to inhibit bacterial growth.
Looking at the regulation, it appears that section 114 describes the use of acidification to preserve foods, but section 113 describes and permits the use of thermal processing as an alternative. This would contradict the books' claim that "all" preserved foods are acidified, and it's consistent with my subjective impression that many canned foods (e.g. beans) don't seem acidic at all.
Is there a blanket regulation that I'm missing? If not, what methods (such as using a pH tester or reading labels to see if they mention citric acid or similar preservatives) can be used to determine whether a particular food has been acidified?