Today I found out why salt enhances flavor.

This is partially simply due to the fact that “saltiness” is one of the five primary basic tastes the human tongue can detect.  Those five tastes being: salt, bitter, sweet, sour, and umami (if you’re not familiar with this one, it is from glutamic acid, which is found in many foods, particularly some meats, and is the basis of the flavor enhancer monosodium glutamate, also known as MSG).

The extra salt has other effects as well though, outside of simply making things more salty.  Particularly, adding salt to foods helps certain molecules in those foods more easily release into the air, thus helping the aroma of the food, which is important in our perception of taste.

Salt also has been shown to help suppress the bitter taste.  So adding a bit of salt won’t just increase your salty taste perception, but will also decrease your bitter taste perception in any given food (which is why it is often sprinkled on grape fruit, for instance, before eating).

Finally, adding salt to sweet or sour things, while not shown to suppress sweet or sour flavors as with bitter flavors, will help balance out the taste a bit by making the perceived flavor, for instance of sugary candies or lemons, less one dimensional.

Bonus Facts:

• The two major components of salt, chloride and sodium ions, are needed by all known living creatures, though in much less quantities than the typical human consumes.  Salt is also involved in the process by which your body regulates its water content (fluid balance).
• All four cationic electrolytes (sodium, potassium, magnesium, and calcium) are found in unrefined salt.
• The word “salad” comes from the ancient Roman practice of salting leaf vegetables; “salad” literally means “salted”.
• Pro-Tip: I learned this trick somewhere years ago and can’t remember where, so can’t source it.  In any event, salt works amazingly well as a stain remover if the stain is from spilled liquid and the spill is recent.  Next time you spill some red wine/Kool-Aid/etc. on the carpet, cover it with a very generous pile of table salt.  Wait an hour or two (the longer the better), then vacuum the salt up.  It is unlikely there will be any stain left behind; at least, in every instance I’ve used this trick, there has been zero trace of the spilled liquid left on the carpet, including spilling red Kool-Aid on white carpet one time.
• Adding salt to water will raise the temperature it boils at and lower the temperature it will freeze at.
• Pro-Tip: if you boil eggs in saltwater, it will make them easier to peel.  Also, if you add a little non-iodized salt to egg whites before whipping them, it will increase the volume and serves as a stabilizer.
• Iodine and an anti-caking agent, typically calcium silicate, are typically added to table salt.  The former is added to help prevent thyroid disease, such as enlargement of the goiter, and the latter so that the salt won’t get lumpy in humid areas.  This anti-caking agent won’t dissolve in water though, so salt containing an anti-caking agent makes a poor choice for pickling and canning.  Salt with iodine added also makes for a poor choice for curing, as the iodine in large enough quantities will add a certain amount of bitterness to the cured food.
• Due to the fact that salt is a mineral, it can be stored more or less indefinitely without going bad or stale.
• Salt has been used as far back as history records to preserve meats, cheeses, and various other foods.  Its preservative nature works by absorbing moisture from the cells of bacteria and mold through osmosis.  This ends up making the mold and bacteria unable to reproduce and ultimately will kill them.
• One of the earliest known salt harvesting facilities dates all the way back to 6000 B.C. in China.  This saltwork harvested salt from the surface of Xiechi Lake near Yuncheng in Shanxi.
• Bamboo salt is a particularly “salty” salt.  It is made by roasting sea salt in bamboo cylinders plugged with mud.  The salt ends up absorbing minerals from the bamboo and mud giving it a somewhat distinct flavor.
• Curing salt is used for curing meats (you never would have guessed that; I know) ;-).  It is made up of 93.75% table salt and 6.25% sodium nitrate.  You’ll often see this dyed pink, so you won’t mistake it with ordinary table salt.
• French sea salt is distinct from most other sea salts in that it is made from sea water that is evaporated out of a basin with the resulting salt not being purified in any way.  So it contains many of the minerals naturally found in sea water.  This tends to be sold for a very high price (as much as $5 for a small packet), even though it is mostly just plain salt and is actually cheaper to make, as it’s unrefined.  Interestingly, many French sea salt factories have relatively recently had to shut down due to rampant water pollution.
• Hawaiian sea salt is very similar to French sea salt, except tends to have a pink-ish hue to it from red Hawaiian volcanic clay, which is rich in iron oxide.
• Sea salt is typically bad for canning or pickling due to the fact that it contains trace minerals that may discolor the food.  The food will likely taste more or less the same in these cases, but will look funny.
• Kosher salt tends to be the preferred salt for chefs.  This salt was originally developed for preparing kosher meats.  Cooks like it for a variety of reasons including: its coarser grains, which make it easier to handle with your fingers, measuring by touch; the larger grains also lend to making salt crusts on meat;  it’s also free of iodine, making it good for pickling things; and iodine can affect certain molecules in some foods and itself has a somewhat bitter taste, so having salt free of iodine is typically preferred.
• Popcorn salt isn’t really any different than table salt except that it is ground much finer than table salt, which allows it to better adhere to popcorn kernels, potato chips, French fries, etc.
• Rock salt is cheap, non-food grade salt.  If you’re wondering how it cannot be food grade, but be used in the making of ice-cream, it doesn’t actually go into the ice cream, as some people think, but rather it goes in the ice-filled area around the tub or bucket of ice cream.  This lowers the freezing point of that ice and causes it to melt, aiding in the process of pulling the heat out of the ice cream in the container.  So basically, the rock salt is used to control the time to freezing of the ice cream in the container.
• The U.S. government mandates that food-grade salt contain at least 97.5% pure salt.