Iodized table salt, for me, it is a pleasant memory… When I was a youngster, we’d all sit together at the dinner table to enjoy a home-cooked meal. Oddly, we salted the food before tasting it to see if it was salty enough already. In those days, the word “salt” referred to Morton salt just as the word “tissue” always meant a Kleenex tissue.
Morton salt came in a midnight-blue cylindrical cardboard box. There was a little girl in a short yellow dress walking in the rain with a somewhat oversized umbrella, spilling the salt as she walked. The motto beneath was “When it rains, it pours.” I always wondered as a kid why the girl was carrying a box of salt that was leaking.
It is odd, but I only realized why yesterday, after more than 70 years! Those many years ago, the price for a box of Morton Salt was a whopping $0.12. The box said the salt was iodized. What does iodized mean, and why did they iodize it?
The chemical formula for table salt is NaCl. Na is sodium, Cl is chlorine. Combined, salt’s chemical name is sodium chloride. The salt that most of us use on our food is nearly pure sodium chloride. However, table salt contains small quantities of three other ingredients: calcium silicate, dextrose, and potassium iodide.
Adding calcium silicate (less than 0.5%) and dextrose (0.04%) were added to enable Morton to state their table salt flows even under humid conditions: “When it rains, it [the salt] pours.”
Although potassium iodide is included in iodized table salt, you can, if you prefer, buy iodide-free salt. What benefit is there to including it? And, why do they use potassium iodide instead of sodium iodide?
Why Potassium Iodide
Both sodium iodide, NaI, and potassium iodide, KI, absorb moisture from the air. In fact, they are both deliquescent. Their being deliquescent means, they are able to absorb enough moisture from the air to dissolve and form a solution! Sodium iodide has a greater tendency to do this than potassium iodide. That’s the reason for choosing KI. The calcium silicate and dextrose assure this does not result in caking.
Iodized Salt: So What’s the Benefit?
Potassium iodide contains potassium metal combined with iodine. The important part of the molecule is the iodine. Iodine is important for the human organism. As Morton itself informs us: Iodine is vital to the proper functioning of the thyroid gland and the prevention of goiter.
So why not add all the vitamins and minerals we need? What is special about iodine? Iodine is not plentiful in the diet of all people. Seafood, a rich source of iodine, was not readily available in land-locked areas, a hundred years ago. Adding just a minimal quantity to table salt, iodizing the salt, was a sensible way to alleviate much of the problem.
Are you the sentimental sort? Then you will likely enjoy this very short video (1:12)…
Finally, speaking of memories… I just tossed this in…
Note: You might also enjoy reading Vanilla and Vanillin: What’s the Difference?