Most folks know that salt is somehow critical to human survival. However, it wasn’t until reading Mark Kurlansky’s book, Salt, that I became aware of just how integral this substance is to the healthy functioning of our bodies and, consequently, the major role it has played in human affairs throughout much of recorded history. As far as our bodies are concerned, the average adult human contains just over a half pound of salt or, as Kurlansky calculates, roughly 3 or 4 salt shakers. However, in the natural course of things, we lose this salt and must take action to replenish it.
Without salt, we get weak, develop headaches, progressing to light-headedness and then to nausea. Ultimately, if deprived long enough, we die. However, we never explicitly crave salt. Before animal husbandry was practiced, humans ate wild animals and were able to get enough salt naturally through this meat. However, once humans began raising animals on farms, the animals were no longer free to roam and find sources of salt for themselves. As animals also require salt in their diets (e.g. a cow needs about 10x the amount of an adult human), early man began to take an interest in sourcing salt directly. It is unclear how we, as humans, first became aware of our salt dependency but it seems that by following the trails of salt-seeking herbivores, early man was able to track down sources of salt, be it in liquid or rock form.
Salt became one of the earliest traded commodities and, for millennia, it remained a major force in international trade. Today, given our knowledge of both chemistry and geology, sourcing salt is no longer as challenging. Straight up salt at the supermarket is pretty cheap and most of us consume way more salt than the minimum our bodies require. That said, not all salts are the same and there is a difference between what one generally finds at the supermarket and naturally harvested salts.
In her book, CookWise, Shirley Corriher explains what makes table salt and sea salt different. To summarize her excellent description: most table salts are “dense cubes.” In contrast, salts that are harvested from the surface of a body of water (fleur de sel, Maldon, etc.) are four-sided crystals. As moisture evaporates from a salt flat, the salt crystals begin to take shape as hollow squares. This square then sinks a little bit and another slightly smaller, four-sided square grows on top of that. Gradually, a hollow pyramid structure is built.
Corriher relates that the difference between table salt and sea salt is like the “difference between an ice-cube and a snowflake.” According to her research, “about 90 percent of granular salt dropped onto an inclined surface bounces off, while 95 percent of the flaky pyramid form sticks to the surface.” The other main difference between granular table salt and sea salt – the former is almost purely sodium chloride (i.e. salt) whereas the latter contains sodium chloride and other minerals. The variety and quantity of those minerals depends on where the salt is sourced from. Not only does this lead to variations in flavor and appearance but, as Corriher points out, additional minerals helps encourage gluten development in bread baking.
Bread was an important early food staple for humans and salt was important not only for its mineral content but also because it played a critical role in controlling yeast activity. Before the advent of canning and refrigeration, salt was also critical for the preservation of food, another reason why this commodity was a major driver of international trade. Salt is used to cure prosciutto and salami (the former through exterior application, the latter by being mixed into the ground meat), preserved lemons and vegetables and to dry fish, among other foodstuffs. In fact, another book by Mark Kurlanksy, Cod, details how the ability to preserve that fish allowed humans to embark on lengthy sea voyages and explore the world.
In summary – salt is not only critical to our diets but it has played a critical role in our collective history. For more interesting details on the exact extent of its role, definitely check out Mr. Kurlansky’s book – I have only been able to relate a few of the interesting tidbits he was able to uncover. And, stay tuned for my second salt installment as I taste through some of the more unusual salts we have at the shop!
April 8, 2011: For part II of this post, please click here.