Salt has been a common food ingredient throughout history. The Greeks, Romans, Hebrews, Assyrians, Chinese, and many other civilizations used salt for both preserving food and improving its taste. Some locations evaporated sea water to harvest the salt within it. Other areas mined salt deposits left from ancient seas. Since salt is so useful and only found in certain regions, it was a principle trading commodity anciently.
Salt is such a valuable resource because of its chemical nature. Salt is primarily composed of sodium chloride (NaCl). Sodium is a cation (positively charged ion) and chloride is an anion (negatively charged ion). Their opposite charges attract each other. Sodium and chloride stack on top of each other to form salt crystals.
When put in water, salt crystals dissolve. Water is a polar molecule, meaning one portion of it has a positive charge and the other has a negative charge. The oxygen end of a water molecule is attracted to sodium, and the hydrogens are attracted to chloride. These attractions are enough to break apart the bonds between sodium and chloride.
When salt is dissolved in water it has some interesting effects. Salt increases water’s boiling point and decreases it’s freezing point. So it will take longer for a pot of water to boil if salt is in it. Water with salt in it can be colder than ice, which is helpful in making ice cream at home.
Salt and Flavor
Salt is one of the five basic flavors. (The others are sweet, bitter, acid, and umami.) But salt does more than just taste salty. At really low levels, in concentrations so low the salty flavor can’t be tasted, salt affects other flavors. Small amounts of salt will enhance sweetness and decrease acid and bitter flavors.
Salt as a Preservative
One of the early methods of preserving meats was salting. Now refrigeration and freezing are used most often. But before refrigerators were invented it was hard to keep foods cold enough to prevent spoiling. Drying worked in areas that had hot, sunny days. Packing in ice worked for places that had enough ice build up in the winter. Salting was a great method because it did not rely on these environmental factors.
Salting drys out both the meat and the microorganisms that are on the meat. This works because of osmosis. When large amounts of salt are added, it creates a concentrated salt solution outside the meat. Suddenly cells (including microorganisms) have a lower concentration of salt and higher concentration of water than their surroundings. So water passes out through the cell membranes in an attempt to balance the water concentrations both within and without the cells. This dehydrates cells, which stops their growth. If enough water leaves the cell it can die. This is how salting prevents microorganisms from spoiling meat.
Sea Salt vs Table Salt
Currently, sea salt is a very trendy ingredient. It is marketed as a healthier option, but that is misleading. The argument is that sea salt has a stronger flavor so less of it is needed, thereby reducing sodium intake. But if the same amount of sea salt is used to replace table salt, there are no nutritional benefits. Sea salt and table salt both have about the same amount of sodium.
Sea salts come from evaporated salt water, either from the ocean or another salty body of water. They undergo varying amounts of processing but almost all have fewer processing steps than table salt. Some are only evaporated. Most sea salts have trace minerals which add flavor and sometimes color to the salt. The trace minerals do not make sea salt healthier because the quantities of minerals are so low. Sea salts also vary in coarseness which effects flavor release. Since sea salts have a stronger flavor and more interesting textures, they are great to use for their salt flavor. It is not worth it to use sea salt for recipes that use salt purely to enhance other flavors.
Table salt is typically mined. It goes through more processing than sea salt. This makes a uniform product and removes most of the trace minerals. Most table salts have added iodine which helps prevent iodine deficiencies that can lead to mental retardation and goiters. Table salts also have anti-caking agents such as calcium silicate. Table salts are great to use in baking and other recipes where salt is present to make the other flavors pop. Of course, table salt is great to have at the table too. It is not as interesting as sea salt but it still has that great salty taste.
So which kind of salt do you like to use? Do you have a favorite sea salt?
- Foods: A Scientific Approach, 3rd Edition, by Helen Charley and Connie Weaver
- Modern Food Microbiology, 7th Edition, by James M. Jay, Martin J. Loessner, and David A. Golden
- A Brief History of Salt, Time Magazine, March 15, 1982 (an older article that nicely summarizes all the other historically information I found)