I've had a couple notes from my science-major sorority sisters regarding calcium chloride and citric acid. Alima's background in chemistry and Mugs's in biomedical engineering probably mean that they know more than I do about this, so I'm going to replay their suggestions and gauge the internet's thoughts. Feel free to weigh in:
*There are many salts in the world, and calcium chloride is one of them. Mugs contends that salt (obvs) is natural, and if I'm eating NaCl, there's no reason why I shouldn't also be comfortable with CaCl2. Without understanding the differences between the combinations, I wiki-ed calcium chloride and came back with the following:
Calcium Chloride is a common salt. It behaves as a typical ionic halide, and is solid at room temperature. It has several common applications such as brine for refrigeration plants, ice and dust control on roads, and in concrete. The anhydrous salt is also widely used as a desiccant, where it will adsorb so much water that it will eventually dissolve in its own crystal lattice water. It can be produced directly from limestone, but large amounts are also produced as a by-product of the Solvay process. Because of its hygroscopic nature, the anhydrous form must be kept in tightly-sealed containers. It is used to turn kelp into a solid.
If any of you can make heads or tails of this, please let me know.
*Meanwhile, Alima told me that citric acid is a naturally occurring acid, appearing in nearly all living things. This sounds pretty persuasive to me -- I mean, if it's in my body whether I intake it or not, that's pretty dang natural -- but I'm still concerned about the process of extraction. Much like my discussion of pectin the other day, does the powder form of citric acid, extracted from something and then added to another, count as "whole"?
Of course, both women pointed out that these (natural) additives are only likely used as stabilizers -- if I'm going to be eating canned anything, it's going to have some kind of salt, etc, in it. So maybe the right answer is to, as Pollan himself suggests, eat fresh and local as much as possible and avoid eating out of season. When I can't do that, the cans and their attendant salts and citruses will have to do.